diff --git a/src/browser/env.zig b/src/browser/env.zig
index c6f0469c3..d7a20cf0d 100644
--- a/src/browser/env.zig
+++ b/src/browser/env.zig
@@ -36,6 +36,8 @@ const WebApis = struct {
         @import("xhr/form_data.zig").Interfaces,
         @import("xhr/File.zig"),
         @import("xmlserializer/xmlserializer.zig").Interfaces,
+        @import("fetch/fetch.zig").Interfaces,
+        @import("streams/streams.zig").Interfaces,
     });
 };
 
diff --git a/src/browser/fetch/Headers.zig b/src/browser/fetch/Headers.zig
new file mode 100644
index 000000000..f7d83c3fd
--- /dev/null
+++ b/src/browser/fetch/Headers.zig
@@ -0,0 +1,227 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../../log.zig");
+const URL = @import("../../url.zig").URL;
+const Page = @import("../page.zig").Page;
+
+const iterator = @import("../iterator/iterator.zig");
+
+const v8 = @import("v8");
+const Env = @import("../env.zig").Env;
+
+// https://developer.mozilla.org/en-US/docs/Web/API/Headers
+const Headers = @This();
+
+// Case-Insensitive String HashMap.
+// This allows us to avoid having to allocate lowercase keys all the time.
+const HeaderHashMap = std.HashMapUnmanaged([]const u8, []const u8, struct {
+    pub fn hash(_: @This(), s: []const u8) u64 {
+        var buf: [64]u8 = undefined;
+        var hasher = std.hash.Wyhash.init(s.len);
+
+        var key = s;
+        while (key.len >= 64) {
+            const lower = std.ascii.lowerString(buf[0..], key[0..64]);
+            hasher.update(lower);
+            key = key[64..];
+        }
+
+        if (key.len > 0) {
+            const lower = std.ascii.lowerString(buf[0..key.len], key);
+            hasher.update(lower);
+        }
+
+        return hasher.final();
+    }
+
+    pub fn eql(_: @This(), a: []const u8, b: []const u8) bool {
+        return std.ascii.eqlIgnoreCase(a, b);
+    }
+}, 80);
+
+headers: HeaderHashMap = .empty,
+
+// They can either be:
+//
+// 1. An array of string pairs.
+// 2. An object with string keys to string values.
+// 3. Another Headers object.
+pub const HeadersInit = union(enum) {
+    // List of Pairs of []const u8
+    strings: []const [2][]const u8,
+    // Headers
+    headers: *Headers,
+    // Mappings
+    object: Env.JsObject,
+};
+
+pub fn constructor(_init: ?HeadersInit, page: *Page) !Headers {
+    const arena = page.arena;
+    var headers: HeaderHashMap = .empty;
+
+    if (_init) |init| {
+        switch (init) {
+            .strings => |kvs| {
+                for (kvs) |pair| {
+                    const key = try arena.dupe(u8, pair[0]);
+                    const value = try arena.dupe(u8, pair[1]);
+
+                    try headers.put(arena, key, value);
+                }
+            },
+            .headers => |hdrs| {
+                var iter = hdrs.headers.iterator();
+                while (iter.next()) |entry| {
+                    try headers.put(arena, entry.key_ptr.*, entry.value_ptr.*);
+                }
+            },
+            .object => |obj| {
+                var iter = obj.nameIterator();
+                while (try iter.next()) |name_value| {
+                    const name = try name_value.toString(arena);
+                    const value = try obj.get(name);
+                    const value_string = try value.toString(arena);
+
+                    try headers.put(arena, name, value_string);
+                }
+            },
+        }
+    }
+
+    return .{
+        .headers = headers,
+    };
+}
+
+pub fn append(self: *Headers, name: []const u8, value: []const u8, allocator: std.mem.Allocator) !void {
+    const key = try allocator.dupe(u8, name);
+    const gop = try self.headers.getOrPut(allocator, key);
+
+    if (gop.found_existing) {
+        // If we found it, append the value.
+        const new_value = try std.fmt.allocPrint(allocator, "{s}, {s}", .{ gop.value_ptr.*, value });
+        gop.value_ptr.* = new_value;
+    } else {
+        // Otherwise, we should just put it in.
+        gop.value_ptr.* = try allocator.dupe(u8, value);
+    }
+}
+
+pub fn _append(self: *Headers, name: []const u8, value: []const u8, page: *Page) !void {
+    const arena = page.arena;
+    try self.append(name, value, arena);
+}
+
+pub fn _delete(self: *Headers, name: []const u8) void {
+    _ = self.headers.remove(name);
+}
+
+pub const HeadersEntryIterator = struct {
+    slot: [2][]const u8,
+    iter: HeaderHashMap.Iterator,
+
+    // TODO: these SHOULD be in lexigraphical order but I'm not sure how actually
+    // important that is.
+    pub fn _next(self: *HeadersEntryIterator) ?[2][]const u8 {
+        if (self.iter.next()) |entry| {
+            self.slot[0] = entry.key_ptr.*;
+            self.slot[1] = entry.value_ptr.*;
+            return self.slot;
+        } else {
+            return null;
+        }
+    }
+};
+
+pub fn _entries(self: *const Headers) HeadersEntryIterable {
+    return .{
+        .inner = .{
+            .slot = undefined,
+            .iter = self.headers.iterator(),
+        },
+    };
+}
+
+pub fn _forEach(self: *Headers, callback_fn: Env.Function, this_arg: ?Env.JsObject) !void {
+    var iter = self.headers.iterator();
+
+    const cb = if (this_arg) |this| try callback_fn.withThis(this) else callback_fn;
+
+    while (iter.next()) |entry| {
+        try cb.call(void, .{ entry.key_ptr.*, entry.value_ptr.*, self });
+    }
+}
+
+pub fn _get(self: *const Headers, name: []const u8) ?[]const u8 {
+    return self.headers.get(name);
+}
+
+pub fn _has(self: *const Headers, name: []const u8) bool {
+    return self.headers.contains(name);
+}
+
+pub const HeadersKeyIterator = struct {
+    iter: HeaderHashMap.KeyIterator,
+
+    pub fn _next(self: *HeadersKeyIterator) ?[]const u8 {
+        if (self.iter.next()) |key| {
+            return key.*;
+        } else {
+            return null;
+        }
+    }
+};
+
+pub fn _keys(self: *const Headers) HeadersKeyIterable {
+    return .{ .inner = .{ .iter = self.headers.keyIterator() } };
+}
+
+pub fn _set(self: *Headers, name: []const u8, value: []const u8, page: *Page) !void {
+    const arena = page.arena;
+
+    const key = try arena.dupe(u8, name);
+    const gop = try self.headers.getOrPut(arena, key);
+    gop.value_ptr.* = try arena.dupe(u8, value);
+}
+
+pub const HeadersValueIterator = struct {
+    iter: HeaderHashMap.ValueIterator,
+
+    pub fn _next(self: *HeadersValueIterator) ?[]const u8 {
+        if (self.iter.next()) |value| {
+            return value.*;
+        } else {
+            return null;
+        }
+    }
+};
+
+pub fn _values(self: *const Headers) HeadersValueIterable {
+    return .{ .inner = .{ .iter = self.headers.valueIterator() } };
+}
+
+pub const HeadersKeyIterable = iterator.Iterable(HeadersKeyIterator, "HeadersKeyIterator");
+pub const HeadersValueIterable = iterator.Iterable(HeadersValueIterator, "HeadersValueIterator");
+pub const HeadersEntryIterable = iterator.Iterable(HeadersEntryIterator, "HeadersEntryIterator");
+
+const testing = @import("../../testing.zig");
+test "fetch: Headers" {
+    try testing.htmlRunner("fetch/headers.html");
+}
diff --git a/src/browser/fetch/Request.zig b/src/browser/fetch/Request.zig
new file mode 100644
index 000000000..7cfc77c29
--- /dev/null
+++ b/src/browser/fetch/Request.zig
@@ -0,0 +1,266 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../../log.zig");
+
+const URL = @import("../../url.zig").URL;
+const Page = @import("../page.zig").Page;
+
+const Response = @import("./Response.zig");
+const Http = @import("../../http/Http.zig");
+const ReadableStream = @import("../streams/ReadableStream.zig");
+
+const v8 = @import("v8");
+const Env = @import("../env.zig").Env;
+
+const Headers = @import("Headers.zig");
+const HeadersInit = @import("Headers.zig").HeadersInit;
+
+pub const RequestInput = union(enum) {
+    string: []const u8,
+    request: *Request,
+};
+
+pub const RequestCache = enum {
+    default,
+    @"no-store",
+    reload,
+    @"no-cache",
+    @"force-cache",
+    @"only-if-cached",
+
+    pub fn fromString(str: []const u8) ?RequestCache {
+        for (std.enums.values(RequestCache)) |cache| {
+            if (std.ascii.eqlIgnoreCase(str, @tagName(cache))) {
+                return cache;
+            }
+        } else {
+            return null;
+        }
+    }
+
+    pub fn toString(self: RequestCache) []const u8 {
+        return @tagName(self);
+    }
+};
+
+pub const RequestCredentials = enum {
+    omit,
+    @"same-origin",
+    include,
+
+    pub fn fromString(str: []const u8) ?RequestCredentials {
+        for (std.enums.values(RequestCredentials)) |cache| {
+            if (std.ascii.eqlIgnoreCase(str, @tagName(cache))) {
+                return cache;
+            }
+        } else {
+            return null;
+        }
+    }
+
+    pub fn toString(self: RequestCredentials) []const u8 {
+        return @tagName(self);
+    }
+};
+
+// https://developer.mozilla.org/en-US/docs/Web/API/RequestInit
+pub const RequestInit = struct {
+    body: ?[]const u8 = null,
+    cache: ?[]const u8 = null,
+    credentials: ?[]const u8 = null,
+    headers: ?HeadersInit = null,
+    integrity: ?[]const u8 = null,
+    method: ?[]const u8 = null,
+};
+
+// https://developer.mozilla.org/en-US/docs/Web/API/Request/Request
+const Request = @This();
+
+method: Http.Method,
+url: [:0]const u8,
+cache: RequestCache,
+credentials: RequestCredentials,
+headers: Headers,
+body: ?[]const u8,
+body_used: bool = false,
+integrity: []const u8,
+
+pub fn constructor(input: RequestInput, _options: ?RequestInit, page: *Page) !Request {
+    const arena = page.arena;
+    const options: RequestInit = _options orelse .{};
+
+    const url: [:0]const u8 = blk: switch (input) {
+        .string => |str| {
+            break :blk try URL.stitch(arena, str, page.url.raw, .{ .null_terminated = true });
+        },
+        .request => |req| {
+            break :blk try arena.dupeZ(u8, req.url);
+        },
+    };
+
+    const body = if (options.body) |body| try arena.dupe(u8, body) else null;
+    const cache = (if (options.cache) |cache| RequestCache.fromString(cache) else null) orelse RequestCache.default;
+    const credentials = (if (options.credentials) |creds| RequestCredentials.fromString(creds) else null) orelse RequestCredentials.@"same-origin";
+    const integrity = if (options.integrity) |integ| try arena.dupe(u8, integ) else "";
+    const headers: Headers = if (options.headers) |hdrs| try Headers.constructor(hdrs, page) else .{};
+
+    const method: Http.Method = blk: {
+        if (options.method) |given_method| {
+            for (std.enums.values(Http.Method)) |method| {
+                if (std.ascii.eqlIgnoreCase(given_method, @tagName(method))) {
+                    break :blk method;
+                }
+            } else {
+                return error.TypeError;
+            }
+        } else {
+            break :blk Http.Method.GET;
+        }
+    };
+
+    return .{
+        .method = method,
+        .url = url,
+        .cache = cache,
+        .credentials = credentials,
+        .headers = headers,
+        .body = body,
+        .integrity = integrity,
+    };
+}
+
+pub fn get_body(self: *const Request, page: *Page) !?*ReadableStream {
+    if (self.body) |body| {
+        const stream = try ReadableStream.constructor(null, null, page);
+        try stream.queue.append(page.arena, body);
+        return stream;
+    } else return null;
+}
+
+pub fn get_bodyUsed(self: *const Request) bool {
+    return self.body_used;
+}
+
+pub fn get_cache(self: *const Request) RequestCache {
+    return self.cache;
+}
+
+pub fn get_credentials(self: *const Request) RequestCredentials {
+    return self.credentials;
+}
+
+pub fn get_headers(self: *Request) *Headers {
+    return &self.headers;
+}
+
+pub fn get_integrity(self: *const Request) []const u8 {
+    return self.integrity;
+}
+
+// TODO: If we ever support the Navigation API, we need isHistoryNavigation
+// https://developer.mozilla.org/en-US/docs/Web/API/Request/isHistoryNavigation
+
+pub fn get_method(self: *const Request) []const u8 {
+    return @tagName(self.method);
+}
+
+pub fn get_url(/service/self: *const Request) []const u8 {
+    return self.url;
+}
+
+pub fn _clone(self: *Request) !Request {
+    // Not allowed to clone if the body was used.
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    // OK to just return the same fields BECAUSE
+    // all of these fields are read-only and can't be modified.
+    return Request{
+        .body = self.body,
+        .body_used = self.body_used,
+        .cache = self.cache,
+        .credentials = self.credentials,
+        .headers = self.headers,
+        .method = self.method,
+        .integrity = self.integrity,
+        .url = self.url,
+    };
+}
+
+pub fn _bytes(self: *Response, page: *Page) !Env.Promise {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    const resolver = Env.PromiseResolver{
+        .js_context = page.main_context,
+        .resolver = v8.PromiseResolver.init(page.main_context.v8_context),
+    };
+
+    try resolver.resolve(self.body);
+    self.body_used = true;
+    return resolver.promise();
+}
+
+pub fn _json(self: *Response, page: *Page) !Env.Promise {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    const resolver = Env.PromiseResolver{
+        .js_context = page.main_context,
+        .resolver = v8.PromiseResolver.init(page.main_context.v8_context),
+    };
+
+    const p = std.json.parseFromSliceLeaky(
+        std.json.Value,
+        page.call_arena,
+        self.body,
+        .{},
+    ) catch |e| {
+        log.info(.browser, "invalid json", .{ .err = e, .source = "Request" });
+        return error.SyntaxError;
+    };
+
+    try resolver.resolve(p);
+    self.body_used = true;
+    return resolver.promise();
+}
+
+pub fn _text(self: *Response, page: *Page) !Env.Promise {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    const resolver = Env.PromiseResolver{
+        .js_context = page.main_context,
+        .resolver = v8.PromiseResolver.init(page.main_context.v8_context),
+    };
+
+    try resolver.resolve(self.body);
+    self.body_used = true;
+    return resolver.promise();
+}
+
+const testing = @import("../../testing.zig");
+test "fetch: Request" {
+    try testing.htmlRunner("fetch/request.html");
+}
diff --git a/src/browser/fetch/Response.zig b/src/browser/fetch/Response.zig
new file mode 100644
index 000000000..af1b615e4
--- /dev/null
+++ b/src/browser/fetch/Response.zig
@@ -0,0 +1,196 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../../log.zig");
+
+const v8 = @import("v8");
+
+const HttpClient = @import("../../http/Client.zig");
+const Http = @import("../../http/Http.zig");
+const URL = @import("../../url.zig").URL;
+
+const ReadableStream = @import("../streams/ReadableStream.zig");
+const Headers = @import("Headers.zig");
+const HeadersInit = @import("Headers.zig").HeadersInit;
+
+const Env = @import("../env.zig").Env;
+const Mime = @import("../mime.zig").Mime;
+const Page = @import("../page.zig").Page;
+
+// https://developer.mozilla.org/en-US/docs/Web/API/Response
+const Response = @This();
+
+status: u16 = 200,
+status_text: []const u8 = "",
+headers: Headers,
+mime: ?Mime = null,
+url: []const u8 = "",
+body: []const u8 = "",
+body_used: bool = false,
+redirected: bool = false,
+
+const ResponseBody = union(enum) {
+    string: []const u8,
+};
+
+const ResponseOptions = struct {
+    status: u16 = 200,
+    statusText: ?[]const u8 = null,
+    headers: ?HeadersInit = null,
+};
+
+pub fn constructor(_input: ?ResponseBody, _options: ?ResponseOptions, page: *Page) !Response {
+    const arena = page.arena;
+
+    const options: ResponseOptions = _options orelse .{};
+
+    const body = blk: {
+        if (_input) |input| {
+            switch (input) {
+                .string => |str| {
+                    break :blk try arena.dupe(u8, str);
+                },
+            }
+        } else {
+            break :blk "";
+        }
+    };
+
+    const headers: Headers = if (options.headers) |hdrs| try Headers.constructor(hdrs, page) else .{};
+    const status_text = if (options.statusText) |st| try arena.dupe(u8, st) else "";
+
+    return .{
+        .body = body,
+        .headers = headers,
+        .status = options.status,
+        .status_text = status_text,
+    };
+}
+
+pub fn get_body(self: *const Response, page: *Page) !*ReadableStream {
+    const stream = try ReadableStream.constructor(null, null, page);
+    try stream.queue.append(page.arena, self.body);
+    return stream;
+}
+
+pub fn get_bodyUsed(self: *const Response) bool {
+    return self.body_used;
+}
+
+pub fn get_headers(self: *Response) *Headers {
+    return &self.headers;
+}
+
+pub fn get_ok(self: *const Response) bool {
+    return self.status >= 200 and self.status <= 299;
+}
+
+pub fn get_redirected(self: *const Response) bool {
+    return self.redirected;
+}
+
+pub fn get_status(self: *const Response) u16 {
+    return self.status;
+}
+
+pub fn get_statusText(self: *const Response) []const u8 {
+    return self.status_text;
+}
+
+pub fn get_url(/service/self: *const Response) []const u8 {
+    return self.url;
+}
+
+pub fn _clone(self: *const Response) !Response {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    // OK to just return the same fields BECAUSE
+    // all of these fields are read-only and can't be modified.
+    return Response{
+        .body = self.body,
+        .body_used = self.body_used,
+        .mime = self.mime,
+        .headers = self.headers,
+        .redirected = self.redirected,
+        .status = self.status,
+        .url = self.url,
+    };
+}
+
+pub fn _bytes(self: *Response, page: *Page) !Env.Promise {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    const resolver = Env.PromiseResolver{
+        .js_context = page.main_context,
+        .resolver = v8.PromiseResolver.init(page.main_context.v8_context),
+    };
+
+    try resolver.resolve(self.body);
+    self.body_used = true;
+    return resolver.promise();
+}
+
+pub fn _json(self: *Response, page: *Page) !Env.Promise {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    const resolver = Env.PromiseResolver{
+        .js_context = page.main_context,
+        .resolver = v8.PromiseResolver.init(page.main_context.v8_context),
+    };
+
+    const p = std.json.parseFromSliceLeaky(
+        std.json.Value,
+        page.call_arena,
+        self.body,
+        .{},
+    ) catch |e| {
+        log.info(.browser, "invalid json", .{ .err = e, .source = "Response" });
+        return error.SyntaxError;
+    };
+
+    try resolver.resolve(p);
+    self.body_used = true;
+    return resolver.promise();
+}
+
+pub fn _text(self: *Response, page: *Page) !Env.Promise {
+    if (self.body_used) {
+        return error.TypeError;
+    }
+
+    const resolver = Env.PromiseResolver{
+        .js_context = page.main_context,
+        .resolver = v8.PromiseResolver.init(page.main_context.v8_context),
+    };
+
+    try resolver.resolve(self.body);
+    self.body_used = true;
+    return resolver.promise();
+}
+
+const testing = @import("../../testing.zig");
+test "fetch: Response" {
+    try testing.htmlRunner("fetch/response.html");
+}
diff --git a/src/browser/fetch/fetch.zig b/src/browser/fetch/fetch.zig
new file mode 100644
index 000000000..1feab0e02
--- /dev/null
+++ b/src/browser/fetch/fetch.zig
@@ -0,0 +1,212 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../../log.zig");
+
+const Env = @import("../env.zig").Env;
+const Page = @import("../page.zig").Page;
+
+const Http = @import("../../http/Http.zig");
+const HttpClient = @import("../../http/Client.zig");
+const Mime = @import("../mime.zig").Mime;
+
+const Headers = @import("Headers.zig");
+
+const RequestInput = @import("Request.zig").RequestInput;
+const RequestInit = @import("Request.zig").RequestInit;
+const Request = @import("Request.zig");
+const Response = @import("Response.zig");
+
+pub const Interfaces = .{
+    @import("Headers.zig"),
+    @import("Headers.zig").HeadersEntryIterable,
+    @import("Headers.zig").HeadersKeyIterable,
+    @import("Headers.zig").HeadersValueIterable,
+    @import("Request.zig"),
+    @import("Response.zig"),
+};
+
+pub const FetchContext = struct {
+    arena: std.mem.Allocator,
+    js_ctx: *Env.JsContext,
+    promise_resolver: Env.PersistentPromiseResolver,
+
+    method: Http.Method,
+    url: []const u8,
+    body: std.ArrayListUnmanaged(u8) = .empty,
+    headers: std.ArrayListUnmanaged([]const u8) = .empty,
+    status: u16 = 0,
+    mime: ?Mime = null,
+    transfer: ?*HttpClient.Transfer = null,
+
+    /// This effectively takes ownership of the FetchContext.
+    ///
+    /// We just return the underlying slices used for `headers`
+    /// and for `body` here to avoid an allocation.
+    pub fn toResponse(self: *const FetchContext) !Response {
+        var headers: Headers = .{};
+
+        // convert into Headers
+        for (self.headers.items) |hdr| {
+            var iter = std.mem.splitScalar(u8, hdr, ':');
+            const name = iter.next() orelse "";
+            const value = iter.next() orelse "";
+            try headers.append(name, value, self.arena);
+        }
+
+        return Response{
+            .status = self.status,
+            .headers = headers,
+            .mime = self.mime,
+            .body = self.body.items,
+            .url = self.url,
+        };
+    }
+};
+
+// https://developer.mozilla.org/en-US/docs/Web/API/Window/fetch
+pub fn fetch(input: RequestInput, options: ?RequestInit, page: *Page) !Env.Promise {
+    const arena = page.arena;
+
+    const req = try Request.constructor(input, options, page);
+    var headers = try Http.Headers.init();
+
+    // Copy our headers into the HTTP headers.
+    var header_iter = req.headers.headers.iterator();
+    while (header_iter.next()) |entry| {
+        const combined = try std.fmt.allocPrintSentinel(
+            page.arena,
+            "{s}: {s}",
+            .{ entry.key_ptr.*, entry.value_ptr.* },
+            0,
+        );
+        try headers.add(combined.ptr);
+    }
+
+    try page.requestCookie(.{}).headersForRequest(arena, req.url, &headers);
+
+    const resolver = try page.main_context.createPersistentPromiseResolver();
+
+    const fetch_ctx = try arena.create(FetchContext);
+    fetch_ctx.* = .{
+        .arena = arena,
+        .js_ctx = page.main_context,
+        .promise_resolver = resolver,
+        .method = req.method,
+        .url = req.url,
+    };
+
+    try page.http_client.request(.{
+        .ctx = @ptrCast(fetch_ctx),
+        .url = req.url,
+        .method = req.method,
+        .headers = headers,
+        .body = req.body,
+        .cookie_jar = page.cookie_jar,
+        .resource_type = .fetch,
+
+        .start_callback = struct {
+            fn startCallback(transfer: *HttpClient.Transfer) !void {
+                const self: *FetchContext = @ptrCast(@alignCast(transfer.ctx));
+                log.debug(.fetch, "request start", .{ .method = self.method, .url = self.url, .source = "fetch" });
+
+                self.transfer = transfer;
+            }
+        }.startCallback,
+        .header_callback = struct {
+            fn headerCallback(transfer: *HttpClient.Transfer) !void {
+                const self: *FetchContext = @ptrCast(@alignCast(transfer.ctx));
+
+                const header = &transfer.response_header.?;
+
+                log.debug(.fetch, "request header", .{
+                    .source = "fetch",
+                    .method = self.method,
+                    .url = self.url,
+                    .status = header.status,
+                });
+
+                if (header.contentType()) |ct| {
+                    self.mime = Mime.parse(ct) catch {
+                        return error.MimeParsing;
+                    };
+                }
+
+                if (transfer.getContentLength()) |cl| {
+                    try self.body.ensureTotalCapacity(self.arena, cl);
+                }
+
+                var it = transfer.responseHeaderIterator();
+                while (it.next()) |hdr| {
+                    const joined = try std.fmt.allocPrint(self.arena, "{s}: {s}", .{ hdr.name, hdr.value });
+                    try self.headers.append(self.arena, joined);
+                }
+
+                self.status = header.status;
+            }
+        }.headerCallback,
+        .data_callback = struct {
+            fn dataCallback(transfer: *HttpClient.Transfer, data: []const u8) !void {
+                const self: *FetchContext = @ptrCast(@alignCast(transfer.ctx));
+                try self.body.appendSlice(self.arena, data);
+            }
+        }.dataCallback,
+        .done_callback = struct {
+            fn doneCallback(ctx: *anyopaque) !void {
+                const self: *FetchContext = @ptrCast(@alignCast(ctx));
+                self.transfer = null;
+
+                log.info(.fetch, "request complete", .{
+                    .source = "fetch",
+                    .method = self.method,
+                    .url = self.url,
+                    .status = self.status,
+                });
+
+                const response = try self.toResponse();
+                try self.promise_resolver.resolve(response);
+            }
+        }.doneCallback,
+        .error_callback = struct {
+            fn errorCallback(ctx: *anyopaque, err: anyerror) void {
+                const self: *FetchContext = @ptrCast(@alignCast(ctx));
+                self.transfer = null;
+
+                log.err(.fetch, "error", .{
+                    .url = self.url,
+                    .err = err,
+                    .source = "fetch error",
+                });
+
+                // We throw an Abort error when the page is getting closed so,
+                // in this case, we don't need to reject the promise.
+                if (err != error.Abort) {
+                    self.promise_resolver.reject(@errorName(err)) catch unreachable;
+                }
+            }
+        }.errorCallback,
+    });
+
+    return resolver.promise();
+}
+
+const testing = @import("../../testing.zig");
+test "fetch: fetch" {
+    try testing.htmlRunner("fetch/fetch.html");
+}
diff --git a/src/browser/html/elements.zig b/src/browser/html/elements.zig
index 5b5fdcd75..5a9121557 100644
--- a/src/browser/html/elements.zig
+++ b/src/browser/html/elements.zig
@@ -1042,84 +1042,68 @@ pub const HTMLSlotElement = struct {
         flatten: bool = false,
     };
     pub fn _assignedNodes(self: *parser.Slot, opts_: ?AssignedNodesOpts, page: *Page) ![]NodeUnion {
-        return findAssignedSlotNodes(self, opts_, false, page);
-    }
-
-    // This should return Union, instead of NodeUnion, but we want to re-use
-    // findAssignedSlotNodes. Returning NodeUnion is fine, as long as every element
-    // within is an Element. This could be more efficient
-    pub fn _assignedElements(self: *parser.Slot, opts_: ?AssignedNodesOpts, page: *Page) ![]NodeUnion {
-        return findAssignedSlotNodes(self, opts_, true, page);
-    }
-
-    fn findAssignedSlotNodes(self: *parser.Slot, opts_: ?AssignedNodesOpts, element_only: bool, page: *Page) ![]NodeUnion {
         const opts = opts_ orelse AssignedNodesOpts{ .flatten = false };
 
-        if (opts.flatten) {
-            log.debug(.web_api, "not implemented", .{ .feature = "HTMLSlotElement flatten assignedNodes" });
+        if (try findAssignedSlotNodes(self, opts, page)) |nodes| {
+            return nodes;
         }
 
-        const node: *parser.Node = @ptrCast(@alignCast(self));
+        if (!opts.flatten) {
+            return &.{};
+        }
 
-        // First we look for any explicitly assigned nodes (via the slot attribute)
-        {
-            const slot_name = try parser.elementGetAttribute(@ptrCast(@alignCast(self)), "name");
-            var root = try parser.nodeGetRootNode(node);
-            if (page.getNodeState(root)) |state| {
-                if (state.shadow_root) |sr| {
-                    root = @ptrCast(@alignCast(sr.host));
-                }
-            }
+        const node: *parser.Node = @ptrCast(@alignCast(self));
+        const nl = try parser.nodeGetChildNodes(node);
+        const len = try parser.nodeListLength(nl);
+        if (len == 0) {
+            return &.{};
+        }
 
-            var arr: std.ArrayList(NodeUnion) = .empty;
-            const w = @import("../dom/walker.zig").WalkerChildren{};
-            var next: ?*parser.Node = null;
-            while (true) {
-                next = try w.get_next(root, next) orelse break;
-                if (try parser.nodeType(next.?) != .element) {
-                    if (slot_name == null and !element_only) {
-                        // default slot (with no name), takes everything
-                        try arr.append(page.call_arena, try Node.toInterface(next.?));
-                    }
-                    continue;
-                }
-                const el: *parser.Element = @ptrCast(@alignCast(next.?));
-                const element_slot = try parser.elementGetAttribute(el, "slot");
+        var assigned = try page.call_arena.alloc(NodeUnion, len);
+        var i: usize = 0;
+        while (true) : (i += 1) {
+            const child = try parser.nodeListItem(nl, @intCast(i)) orelse break;
+            assigned[i] = try Node.toInterface(child);
+        }
+        return assigned[0..i];
+    }
 
-                if (nullableStringsAreEqual(slot_name, element_slot)) {
-                    // either they're the same string or they are both null
-                    try arr.append(page.call_arena, try Node.toInterface(next.?));
-                    continue;
-                }
-            }
-            if (arr.items.len > 0) {
-                return arr.items;
-            }
+    fn findAssignedSlotNodes(self: *parser.Slot, opts: AssignedNodesOpts, page: *Page) !?[]NodeUnion {
+        if (opts.flatten) {
+            log.warn(.web_api, "not implemented", .{ .feature = "HTMLSlotElement flatten assignedNodes" });
+        }
 
-            if (!opts.flatten) {
-                return &.{};
+        const slot_name = try parser.elementGetAttribute(@ptrCast(@alignCast(self)), "name");
+        const node: *parser.Node = @ptrCast(@alignCast(self));
+        var root = try parser.nodeGetRootNode(node);
+        if (page.getNodeState(root)) |state| {
+            if (state.shadow_root) |sr| {
+                root = @ptrCast(@alignCast(sr.host));
             }
         }
 
-        // Since, we have no explicitly assigned nodes and flatten == false,
-        // we'll collect the children of the slot - the defaults.
-        {
-            const nl = try parser.nodeGetChildNodes(node);
-            const len = try parser.nodeListLength(nl);
-            if (len == 0) {
-                return &.{};
+        var arr: std.ArrayList(NodeUnion) = .empty;
+        const w = @import("../dom/walker.zig").WalkerChildren{};
+        var next: ?*parser.Node = null;
+        while (true) {
+            next = try w.get_next(root, next) orelse break;
+            if (try parser.nodeType(next.?) != .element) {
+                if (slot_name == null) {
+                    // default slot (with no name), takes everything
+                    try arr.append(page.call_arena, try Node.toInterface(next.?));
+                }
+                continue;
             }
+            const el: *parser.Element = @ptrCast(@alignCast(next.?));
+            const element_slot = try parser.elementGetAttribute(el, "slot");
 
-            var assigned = try page.call_arena.alloc(NodeUnion, len);
-            var i: usize = 0;
-            while (true) : (i += 1) {
-                const child = try parser.nodeListItem(nl, @intCast(i)) orelse break;
-                if (!element_only or try parser.nodeType(child) == .element) {
-                    assigned[i] = try Node.toInterface(child);
-                }
+            if (nullableStringsAreEqual(slot_name, element_slot)) {
+                // either they're the same string or they are both null
+                try arr.append(page.call_arena, try Node.toInterface(next.?));
+                continue;
             }
-            return assigned[0..i];
         }
+        return if (arr.items.len == 0) null else arr.items;
     }
 
     fn nullableStringsAreEqual(a: ?[]const u8, b: ?[]const u8) bool {
@@ -1345,6 +1329,39 @@ test "Browser: HTML.HtmlScriptElement" {
     try testing.htmlRunner("html/script/inline_defer.html");
 }
 
-test "Browser: HTML.HtmlSlotElement" {
-    try testing.htmlRunner("html/slot.html");
+test "Browser: HTML.HTMLSlotElement" {
+    try testing.htmlRunner("html/html_slot_element.html");
+}
+
+const Check = struct {
+    input: []const u8,
+    expected: ?[]const u8 = null, // Needed when input != expected
+};
+const bool_valids = [_]Check{
+    .{ .input = "true" },
+    .{ .input = "''", .expected = "false" },
+    .{ .input = "13.5", .expected = "true" },
+};
+const str_valids = [_]Check{
+    .{ .input = "'foo'", .expected = "foo" },
+    .{ .input = "5", .expected = "5" },
+    .{ .input = "''", .expected = "" },
+    .{ .input = "document", .expected = "[object HTMLDocument]" },
+};
+
+// .{ "elem.type = '5'", "5" },
+// .{ "elem.type", "text" },
+fn testProperty(
+    arena: std.mem.Allocator,
+    runner: *testing.JsRunner,
+    elem_dot_prop: []const u8,
+    always: ?[]const u8, // Ignores checks' expected if set
+    checks: []const Check,
+) !void {
+    for (checks) |check| {
+        try runner.testCases(&.{
+            .{ try std.mem.concat(arena, u8, &.{ elem_dot_prop, " = ", check.input }), null },
+            .{ elem_dot_prop, always orelse check.expected orelse check.input },
+        }, .{});
+    }
 }
diff --git a/src/browser/html/window.zig b/src/browser/html/window.zig
index 6f1d5fe8f..790e823f6 100644
--- a/src/browser/html/window.zig
+++ b/src/browser/html/window.zig
@@ -39,6 +39,10 @@ const Css = @import("../css/css.zig").Css;
 const Function = Env.Function;
 const JsObject = Env.JsObject;
 
+const v8 = @import("v8");
+const Request = @import("../fetch/Request.zig");
+const fetchFn = @import("../fetch/fetch.zig").fetch;
+
 const storage = @import("../storage/storage.zig");
 
 // https://dom.spec.whatwg.org/#interface-window-extensions
@@ -95,6 +99,10 @@ pub const Window = struct {
         self.storage_shelf = shelf;
     }
 
+    pub fn _fetch(_: *Window, input: Request.RequestInput, options: ?Request.RequestInit, page: *Page) !Env.Promise {
+        return fetchFn(input, options, page);
+    }
+
     pub fn get_window(self: *Window) *Window {
         return self;
     }
diff --git a/src/browser/polyfill/fetch.js b/src/browser/polyfill/fetch.js
deleted file mode 100644
index 75efab54c..000000000
--- a/src/browser/polyfill/fetch.js
+++ /dev/null
@@ -1,671 +0,0 @@
-// fetch.js code comes from
-// https://github.com/JakeChampion/fetch/blob/main/fetch.js
-//
-// The original code source is available in MIT license.
-//
-// The script comes from the built version from npm.
-// You can get the package with the command:
-//
-// wget $(npm view whatwg-fetch dist.tarball)
-//
-// The source is the content of `package/dist/fetch.umd.js` file.
-(function (global, factory) {
-  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
-  typeof define === 'function' && define.amd ? define(['exports'], factory) :
-  (factory((global.WHATWGFetch = {})));
-}(this, (function (exports) { 'use strict';
-
-  /* eslint-disable no-prototype-builtins */
-  var g =
-    (typeof globalThis !== 'undefined' && globalThis) ||
-    (typeof self !== 'undefined' && self) ||
-    // eslint-disable-next-line no-undef
-    (typeof global !== 'undefined' && global) ||
-    {};
-
-  var support = {
-    searchParams: 'URLSearchParams' in g,
-    iterable: 'Symbol' in g && 'iterator' in Symbol,
-    blob:
-      'FileReader' in g &&
-      'Blob' in g &&
-      (function() {
-        try {
-          new Blob();
-          return true
-        } catch (e) {
-          return false
-        }
-      })(),
-    formData: 'FormData' in g,
-
-    // Arraybuffer is available but xhr doesn't implement it for now.
-    // arrayBuffer: 'ArrayBuffer' in g
-    arrayBuffer: false
-  };
-
-  function isDataView(obj) {
-    return obj && DataView.prototype.isPrototypeOf(obj)
-  }
-
-  if (support.arrayBuffer) {
-    var viewClasses = [
-      '[object Int8Array]',
-      '[object Uint8Array]',
-      '[object Uint8ClampedArray]',
-      '[object Int16Array]',
-      '[object Uint16Array]',
-      '[object Int32Array]',
-      '[object Uint32Array]',
-      '[object Float32Array]',
-      '[object Float64Array]'
-    ];
-
-    var isArrayBufferView =
-      ArrayBuffer.isView ||
-      function(obj) {
-        return obj && viewClasses.indexOf(Object.prototype.toString.call(obj)) > -1
-      };
-  }
-
-  function normalizeName(name) {
-    if (typeof name !== 'string') {
-      name = String(name);
-    }
-    if (/[^a-z0-9\-#$%&'*+.^_`|~!]/i.test(name) || name === '') {
-      throw new TypeError('Invalid character in header field name: "' + name + '"')
-    }
-    return name.toLowerCase()
-  }
-
-  function normalizeValue(value) {
-    if (typeof value !== 'string') {
-      value = String(value);
-    }
-    return value
-  }
-
-  // Build a destructive iterator for the value list
-  function iteratorFor(items) {
-    var iterator = {
-      next: function() {
-        var value = items.shift();
-        return {done: value === undefined, value: value}
-      }
-    };
-
-    if (support.iterable) {
-      iterator[Symbol.iterator] = function() {
-        return iterator
-      };
-    }
-
-    return iterator
-  }
-
-  function Headers(headers) {
-    this.map = {};
-
-    if (headers instanceof Headers) {
-      headers.forEach(function(value, name) {
-        this.append(name, value);
-      }, this);
-    } else if (Array.isArray(headers)) {
-      headers.forEach(function(header) {
-        if (header.length != 2) {
-          throw new TypeError('Headers constructor: expected name/value pair to be length 2, found' + header.length)
-        }
-        this.append(header[0], header[1]);
-      }, this);
-    } else if (headers) {
-      Object.getOwnPropertyNames(headers).forEach(function(name) {
-        this.append(name, headers[name]);
-      }, this);
-    }
-  }
-
-  Headers.prototype.append = function(name, value) {
-    name = normalizeName(name);
-    value = normalizeValue(value);
-    var oldValue = this.map[name];
-    this.map[name] = oldValue ? oldValue + ', ' + value : value;
-  };
-
-  Headers.prototype['delete'] = function(name) {
-    delete this.map[normalizeName(name)];
-  };
-
-  Headers.prototype.get = function(name) {
-    name = normalizeName(name);
-    return this.has(name) ? this.map[name] : null
-  };
-
-  Headers.prototype.has = function(name) {
-    return this.map.hasOwnProperty(normalizeName(name))
-  };
-
-  Headers.prototype.set = function(name, value) {
-    this.map[normalizeName(name)] = normalizeValue(value);
-  };
-
-  Headers.prototype.forEach = function(callback, thisArg) {
-    for (var name in this.map) {
-      if (this.map.hasOwnProperty(name)) {
-        callback.call(thisArg, this.map[name], name, this);
-      }
-    }
-  };
-
-  Headers.prototype.keys = function() {
-    var items = [];
-    this.forEach(function(value, name) {
-      items.push(name);
-    });
-    return iteratorFor(items)
-  };
-
-  Headers.prototype.values = function() {
-    var items = [];
-    this.forEach(function(value) {
-      items.push(value);
-    });
-    return iteratorFor(items)
-  };
-
-  Headers.prototype.entries = function() {
-    var items = [];
-    this.forEach(function(value, name) {
-      items.push([name, value]);
-    });
-    return iteratorFor(items)
-  };
-
-  if (support.iterable) {
-    Headers.prototype[Symbol.iterator] = Headers.prototype.entries;
-  }
-
-  function consumed(body) {
-    if (body._noBody) return
-    if (body.bodyUsed) {
-      return Promise.reject(new TypeError('Already read'))
-    }
-    body.bodyUsed = true;
-  }
-
-  function fileReaderReady(reader) {
-    return new Promise(function(resolve, reject) {
-      reader.onload = function() {
-        resolve(reader.result);
-      };
-      reader.onerror = function() {
-        reject(reader.error);
-      };
-    })
-  }
-
-  function readBlobAsArrayBuffer(blob) {
-    var reader = new FileReader();
-    var promise = fileReaderReady(reader);
-    reader.readAsArrayBuffer(blob);
-    return promise
-  }
-
-  function readBlobAsText(blob) {
-    var reader = new FileReader();
-    var promise = fileReaderReady(reader);
-    var match = /charset=([A-Za-z0-9_-]+)/.exec(blob.type);
-    var encoding = match ? match[1] : 'utf-8';
-    reader.readAsText(blob, encoding);
-    return promise
-  }
-
-  function readArrayBufferAsText(buf) {
-    var view = new Uint8Array(buf);
-    var chars = new Array(view.length);
-
-    for (var i = 0; i < view.length; i++) {
-      chars[i] = String.fromCharCode(view[i]);
-    }
-    return chars.join('')
-  }
-
-  function bufferClone(buf) {
-    if (buf.slice) {
-      return buf.slice(0)
-    } else {
-      var view = new Uint8Array(buf.byteLength);
-      view.set(new Uint8Array(buf));
-      return view.buffer
-    }
-  }
-
-  function Body() {
-    this.bodyUsed = false;
-
-    this._initBody = function(body) {
-      /*
-        fetch-mock wraps the Response object in an ES6 Proxy to
-        provide useful test harness features such as flush. However, on
-        ES5 browsers without fetch or Proxy support pollyfills must be used;
-        the proxy-pollyfill is unable to proxy an attribute unless it exists
-        on the object before the Proxy is created. This change ensures
-        Response.bodyUsed exists on the instance, while maintaining the
-        semantic of setting Request.bodyUsed in the constructor before
-        _initBody is called.
-      */
-      // eslint-disable-next-line no-self-assign
-      this.bodyUsed = this.bodyUsed;
-      this._bodyInit = body;
-      if (!body) {
-        this._noBody = true;
-        this._bodyText = '';
-      } else if (typeof body === 'string') {
-        this._bodyText = body;
-      } else if (support.blob && Blob.prototype.isPrototypeOf(body)) {
-        this._bodyBlob = body;
-      } else if (support.formData && FormData.prototype.isPrototypeOf(body)) {
-        this._bodyFormData = body;
-      } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
-        this._bodyText = body.toString();
-      } else if (support.arrayBuffer && support.blob && isDataView(body)) {
-        this._bodyArrayBuffer = bufferClone(body.buffer);
-        // IE 10-11 can't handle a DataView body.
-        this._bodyInit = new Blob([this._bodyArrayBuffer]);
-      } else if (support.arrayBuffer && (ArrayBuffer.prototype.isPrototypeOf(body) || isArrayBufferView(body))) {
-        this._bodyArrayBuffer = bufferClone(body);
-      } else {
-        this._bodyText = body = Object.prototype.toString.call(body);
-      }
-
-      if (!this.headers.get('content-type')) {
-        if (typeof body === 'string') {
-          this.headers.set('content-type', 'text/plain;charset=UTF-8');
-        } else if (this._bodyBlob && this._bodyBlob.type) {
-          this.headers.set('content-type', this._bodyBlob.type);
-        } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
-          this.headers.set('content-type', 'application/x-www-form-urlencoded;charset=UTF-8');
-        }
-      }
-    };
-
-    if (support.blob) {
-      this.blob = function() {
-        var rejected = consumed(this);
-        if (rejected) {
-          return rejected
-        }
-
-        if (this._bodyBlob) {
-          return Promise.resolve(this._bodyBlob)
-        } else if (this._bodyArrayBuffer) {
-          return Promise.resolve(new Blob([this._bodyArrayBuffer]))
-        } else if (this._bodyFormData) {
-          throw new Error('could not read FormData body as blob')
-        } else {
-          return Promise.resolve(new Blob([this._bodyText]))
-        }
-      };
-    }
-
-    this.arrayBuffer = function() {
-      if (this._bodyArrayBuffer) {
-        var isConsumed = consumed(this);
-        if (isConsumed) {
-          return isConsumed
-        } else if (ArrayBuffer.isView(this._bodyArrayBuffer)) {
-          return Promise.resolve(
-            this._bodyArrayBuffer.buffer.slice(
-              this._bodyArrayBuffer.byteOffset,
-              this._bodyArrayBuffer.byteOffset + this._bodyArrayBuffer.byteLength
-            )
-          )
-        } else {
-          return Promise.resolve(this._bodyArrayBuffer)
-        }
-      } else if (support.blob) {
-        return this.blob().then(readBlobAsArrayBuffer)
-      } else {
-        throw new Error('could not read as ArrayBuffer')
-      }
-    };
-
-    this.text = function() {
-      var rejected = consumed(this);
-      if (rejected) {
-        return rejected
-      }
-
-      if (this._bodyBlob) {
-        return readBlobAsText(this._bodyBlob)
-      } else if (this._bodyArrayBuffer) {
-        return Promise.resolve(readArrayBufferAsText(this._bodyArrayBuffer))
-      } else if (this._bodyFormData) {
-        throw new Error('could not read FormData body as text')
-      } else {
-        return Promise.resolve(this._bodyText)
-      }
-    };
-
-    if (support.formData) {
-      this.formData = function() {
-        return this.text().then(decode)
-      };
-    }
-
-    this.json = function() {
-      return this.text().then(JSON.parse)
-    };
-
-    return this
-  }
-
-  // HTTP methods whose capitalization should be normalized
-  var methods = ['CONNECT', 'DELETE', 'GET', 'HEAD', 'OPTIONS', 'PATCH', 'POST', 'PUT', 'TRACE'];
-
-  function normalizeMethod(method) {
-    var upcased = method.toUpperCase();
-    return methods.indexOf(upcased) > -1 ? upcased : method
-  }
-
-  function Request(input, options) {
-    if (!(this instanceof Request)) {
-      throw new TypeError('Please use the "new" operator, this DOM object constructor cannot be called as a function.')
-    }
-
-    options = options || {};
-    var body = options.body;
-
-    if (input instanceof Request) {
-      if (input.bodyUsed) {
-        throw new TypeError('Already read')
-      }
-      this.url = input.url;
-      this.credentials = input.credentials;
-      if (!options.headers) {
-        this.headers = new Headers(input.headers);
-      }
-      this.method = input.method;
-      this.mode = input.mode;
-      this.signal = input.signal;
-      if (!body && input._bodyInit != null) {
-        body = input._bodyInit;
-        input.bodyUsed = true;
-      }
-    } else {
-      this.url = String(input);
-    }
-
-    this.credentials = options.credentials || this.credentials || 'same-origin';
-    if (options.headers || !this.headers) {
-      this.headers = new Headers(options.headers);
-    }
-    this.method = normalizeMethod(options.method || this.method || 'GET');
-    this.mode = options.mode || this.mode || null;
-    this.signal = options.signal || this.signal || (function () {
-      if ('AbortController' in g) {
-        var ctrl = new AbortController();
-        return ctrl.signal;
-      }
-    }());
-    this.referrer = null;
-
-    if ((this.method === 'GET' || this.method === 'HEAD') && body) {
-      throw new TypeError('Body not allowed for GET or HEAD requests')
-    }
-    this._initBody(body);
-
-    if (this.method === 'GET' || this.method === 'HEAD') {
-      if (options.cache === 'no-store' || options.cache === 'no-cache') {
-        // Search for a '_' parameter in the query string
-        var reParamSearch = /([?&])_=[^&]*/;
-        if (reParamSearch.test(this.url)) {
-          // If it already exists then set the value with the current time
-          this.url = this.url.replace(reParamSearch, '$1_=' + new Date().getTime());
-        } else {
-          // Otherwise add a new '_' parameter to the end with the current time
-          var reQueryString = /\?/;
-          this.url += (reQueryString.test(this.url) ? '&' : '?') + '_=' + new Date().getTime();
-        }
-      }
-    }
-  }
-
-  Request.prototype.clone = function() {
-    return new Request(this, {body: this._bodyInit})
-  };
-
-  function decode(body) {
-    var form = new FormData();
-    body
-      .trim()
-      .split('&')
-      .forEach(function(bytes) {
-        if (bytes) {
-          var split = bytes.split('=');
-          var name = split.shift().replace(/\+/g, ' ');
-          var value = split.join('=').replace(/\+/g, ' ');
-          form.append(decodeURIComponent(name), decodeURIComponent(value));
-        }
-      });
-    return form
-  }
-
-  function parseHeaders(rawHeaders) {
-    var headers = new Headers();
-    // Replace instances of \r\n and \n followed by at least one space or horizontal tab with a space
-    // https://tools.ietf.org/html/rfc7230#section-3.2
-    var preProcessedHeaders = rawHeaders.replace(/\r?\n[\t ]+/g, ' ');
-    // Avoiding split via regex to work around a common IE11 bug with the core-js 3.6.0 regex polyfill
-    // https://github.com/github/fetch/issues/748
-    // https://github.com/zloirock/core-js/issues/751
-    preProcessedHeaders
-      .split('\r')
-      .map(function(header) {
-        return header.indexOf('\n') === 0 ? header.substr(1, header.length) : header
-      })
-      .forEach(function(line) {
-        var parts = line.split(':');
-        var key = parts.shift().trim();
-        if (key) {
-          var value = parts.join(':').trim();
-          try {
-            headers.append(key, value);
-          } catch (error) {
-            console.warn('Response ' + error.message);
-          }
-        }
-      });
-    return headers
-  }
-
-  Body.call(Request.prototype);
-
-  function Response(bodyInit, options) {
-    if (!(this instanceof Response)) {
-      throw new TypeError('Please use the "new" operator, this DOM object constructor cannot be called as a function.')
-    }
-    if (!options) {
-      options = {};
-    }
-
-    this.type = 'default';
-    this.status = options.status === undefined ? 200 : options.status;
-    if (this.status < 200 || this.status > 599) {
-      throw new RangeError("Failed to construct 'Response': The status provided (0) is outside the range [200, 599].")
-    }
-    this.ok = this.status >= 200 && this.status < 300;
-    this.statusText = options.statusText === undefined ? '' : '' + options.statusText;
-    this.headers = new Headers(options.headers);
-    this.url = options.url || '';
-    this._initBody(bodyInit);
-  }
-
-  Body.call(Response.prototype);
-
-  Response.prototype.clone = function() {
-    return new Response(this._bodyInit, {
-      status: this.status,
-      statusText: this.statusText,
-      headers: new Headers(this.headers),
-      url: this.url
-    })
-  };
-
-  Response.error = function() {
-    var response = new Response(null, {status: 200, statusText: ''});
-    response.ok = false;
-    response.status = 0;
-    response.type = 'error';
-    return response
-  };
-
-  var redirectStatuses = [301, 302, 303, 307, 308];
-
-  Response.redirect = function(url, status) {
-    if (redirectStatuses.indexOf(status) === -1) {
-      throw new RangeError('Invalid status code')
-    }
-
-    return new Response(null, {status: status, headers: {location: url}})
-  };
-
-  exports.DOMException = g.DOMException;
-  try {
-    new exports.DOMException();
-  } catch (err) {
-    exports.DOMException = function(message, name) {
-      this.message = message;
-      this.name = name;
-      var error = Error(message);
-      this.stack = error.stack;
-    };
-    exports.DOMException.prototype = Object.create(Error.prototype);
-    exports.DOMException.prototype.constructor = exports.DOMException;
-  }
-
-  function fetch(input, init) {
-    return new Promise(function(resolve, reject) {
-      var request = new Request(input, init);
-
-      if (request.signal && request.signal.aborted) {
-        return reject(new exports.DOMException('Aborted', 'AbortError'))
-      }
-
-      var xhr = new XMLHttpRequest();
-
-      function abortXhr() {
-        xhr.abort();
-      }
-
-      xhr.onload = function() {
-        var options = {
-          statusText: xhr.statusText,
-          headers: parseHeaders(xhr.getAllResponseHeaders() || '')
-        };
-        // This check if specifically for when a user fetches a file locally from the file system
-        // Only if the status is out of a normal range
-        if (request.url.indexOf('file://') === 0 && (xhr.status < 200 || xhr.status > 599)) {
-          options.status = 200;
-        } else {
-          options.status = xhr.status;
-        }
-        options.url = 'responseURL' in xhr ? xhr.responseURL : options.headers.get('X-Request-URL');
-        var body = 'response' in xhr ? xhr.response : xhr.responseText;
-        setTimeout(function() {
-          resolve(new Response(body, options));
-        }, 0);
-      };
-
-      xhr.onerror = function() {
-        setTimeout(function() {
-          reject(new TypeError('Network request failed'));
-        }, 0);
-      };
-
-      xhr.ontimeout = function() {
-        setTimeout(function() {
-          reject(new TypeError('Network request timed out'));
-        }, 0);
-      };
-
-      xhr.onabort = function() {
-        setTimeout(function() {
-          reject(new exports.DOMException('Aborted', 'AbortError'));
-        }, 0);
-      };
-
-      function fixUrl(url) {
-        try {
-          return url === '' && g.location.href ? g.location.href : url
-        } catch (e) {
-          return url
-        }
-      }
-
-      xhr.open(request.method, fixUrl(request.url), true);
-
-      if (request.credentials === 'include') {
-        xhr.withCredentials = true;
-      } else if (request.credentials === 'omit') {
-        xhr.withCredentials = false;
-      }
-
-      if ('responseType' in xhr) {
-        if (support.blob) {
-          xhr.responseType = 'blob';
-        } else if (
-          support.arrayBuffer
-        ) {
-          xhr.responseType = 'arraybuffer';
-        }
-      }
-
-      if (init && typeof init.headers === 'object' && !(init.headers instanceof Headers || (g.Headers && init.headers instanceof g.Headers))) {
-        var names = [];
-        Object.getOwnPropertyNames(init.headers).forEach(function(name) {
-          names.push(normalizeName(name));
-          xhr.setRequestHeader(name, normalizeValue(init.headers[name]));
-        });
-        request.headers.forEach(function(value, name) {
-          if (names.indexOf(name) === -1) {
-            xhr.setRequestHeader(name, value);
-          }
-        });
-      } else {
-        request.headers.forEach(function(value, name) {
-          xhr.setRequestHeader(name, value);
-        });
-      }
-
-      if (request.signal) {
-        request.signal.addEventListener('abort', abortXhr);
-
-        xhr.onreadystatechange = function() {
-          // DONE (success or failure)
-          if (xhr.readyState === 4) {
-            request.signal.removeEventListener('abort', abortXhr);
-          }
-        };
-      }
-
-      xhr.send(typeof request._bodyInit === 'undefined' ? null : request._bodyInit);
-    })
-  }
-
-  fetch.polyfill = true;
-
-  if (!g.fetch) {
-    g.fetch = fetch;
-    g.Headers = Headers;
-    g.Request = Request;
-    g.Response = Response;
-  }
-
-  exports.Headers = Headers;
-  exports.Request = Request;
-  exports.Response = Response;
-  exports.fetch = fetch;
-
-  Object.defineProperty(exports, '__esModule', { value: true });
-
-})));
diff --git a/src/browser/polyfill/fetch.zig b/src/browser/polyfill/fetch.zig
deleted file mode 100644
index 9ed134de7..000000000
--- a/src/browser/polyfill/fetch.zig
+++ /dev/null
@@ -1,31 +0,0 @@
-// fetch.js code comes from
-// https://github.com/JakeChampion/fetch/blob/main/fetch.js
-//
-// The original code source is available in MIT license.
-//
-// The script comes from the built version from npm.
-// You can get the package with the command:
-//
-// wget $(npm view whatwg-fetch dist.tarball)
-//
-// The source is the content of `package/dist/fetch.umd.js` file.
-pub const source = @embedFile("fetch.js");
-
-const testing = @import("../../testing.zig");
-test "Browser.fetch" {
-    var runner = try testing.jsRunner(testing.tracking_allocator, .{});
-    defer runner.deinit();
-
-    try runner.testCases(&.{
-        .{
-            \\  var ok = false;
-            \\  const request = new Request("http://127.0.0.1:9582/loader");
-            \\  fetch(request).then((response) => { ok = response.ok; });
-            \\  false;
-            ,
-            "false",
-        },
-        // all events have been resolved.
-        .{ "ok", "true" },
-    }, .{});
-}
diff --git a/src/browser/polyfill/polyfill.zig b/src/browser/polyfill/polyfill.zig
index 59822c62e..617bdf862 100644
--- a/src/browser/polyfill/polyfill.zig
+++ b/src/browser/polyfill/polyfill.zig
@@ -27,7 +27,6 @@ pub const Loader = struct {
     state: enum { empty, loading } = .empty,
 
     done: struct {
-        fetch: bool = false,
         webcomponents: bool = false,
     } = .{},
 
@@ -56,18 +55,6 @@ pub const Loader = struct {
             return false;
         }
 
-        if (!self.done.fetch and isFetch(name)) {
-            const source = @import("fetch.zig").source;
-            self.load("fetch", source, js_context);
-
-            // We return false here: We want v8 to continue the calling chain
-            // to finally find the polyfill we just inserted. If we want to
-            // return false and stops the call chain, we have to use
-            // `info.GetReturnValue.Set()` function, or `undefined` will be
-            // returned immediately.
-            return false;
-        }
-
         if (!self.done.webcomponents and isWebcomponents(name)) {
             const source = @import("webcomponents.zig").source;
             self.load("webcomponents", source, js_context);
@@ -89,14 +76,6 @@ pub const Loader = struct {
         return false;
     }
 
-    fn isFetch(name: []const u8) bool {
-        if (std.mem.eql(u8, name, "fetch")) return true;
-        if (std.mem.eql(u8, name, "Request")) return true;
-        if (std.mem.eql(u8, name, "Response")) return true;
-        if (std.mem.eql(u8, name, "Headers")) return true;
-        return false;
-    }
-
     fn isWebcomponents(name: []const u8) bool {
         if (std.mem.eql(u8, name, "customElements")) return true;
         return false;
diff --git a/src/browser/streams/ReadableStream.zig b/src/browser/streams/ReadableStream.zig
new file mode 100644
index 000000000..8857c7b31
--- /dev/null
+++ b/src/browser/streams/ReadableStream.zig
@@ -0,0 +1,174 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../../log.zig");
+
+const Page = @import("../page.zig").Page;
+const Env = @import("../env.zig").Env;
+
+const ReadableStream = @This();
+const ReadableStreamDefaultReader = @import("ReadableStreamDefaultReader.zig");
+const ReadableStreamDefaultController = @import("ReadableStreamDefaultController.zig");
+
+const State = union(enum) {
+    readable,
+    closed: ?[]const u8,
+    cancelled: ?[]const u8,
+    errored: Env.JsObject,
+};
+
+// This promise resolves when a stream is canceled.
+cancel_resolver: Env.PersistentPromiseResolver,
+closed_resolver: Env.PersistentPromiseResolver,
+reader_resolver: ?Env.PersistentPromiseResolver = null,
+
+locked: bool = false,
+state: State = .readable,
+
+cancel_fn: ?Env.Function = null,
+pull_fn: ?Env.Function = null,
+
+strategy: QueueingStrategy,
+queue: std.ArrayListUnmanaged([]const u8) = .empty,
+
+pub const ReadableStreamReadResult = struct {
+    const ValueUnion =
+        union(enum) { data: []const u8, empty: void };
+
+    value: ValueUnion,
+    done: bool,
+
+    pub fn get_value(self: *const ReadableStreamReadResult) ValueUnion {
+        return self.value;
+    }
+
+    pub fn get_done(self: *const ReadableStreamReadResult) bool {
+        return self.done;
+    }
+};
+
+const UnderlyingSource = struct {
+    start: ?Env.Function = null,
+    pull: ?Env.Function = null,
+    cancel: ?Env.Function = null,
+    type: ?[]const u8 = null,
+};
+
+const QueueingStrategy = struct {
+    size: ?Env.Function = null,
+    high_water_mark: u32 = 1,
+};
+
+pub fn constructor(underlying: ?UnderlyingSource, _strategy: ?QueueingStrategy, page: *Page) !*ReadableStream {
+    const strategy: QueueingStrategy = _strategy orelse .{};
+
+    const cancel_resolver = try page.main_context.createPersistentPromiseResolver();
+    const closed_resolver = try page.main_context.createPersistentPromiseResolver();
+
+    const stream = try page.arena.create(ReadableStream);
+    stream.* = ReadableStream{ .cancel_resolver = cancel_resolver, .closed_resolver = closed_resolver, .strategy = strategy };
+
+    const controller = ReadableStreamDefaultController{ .stream = stream };
+
+    // call start
+    if (underlying) |src| {
+        if (src.start) |start| {
+            try start.call(void, .{controller});
+        }
+
+        if (src.cancel) |cancel| {
+            stream.cancel_fn = cancel;
+        }
+
+        if (src.pull) |pull| {
+            stream.pull_fn = pull;
+            try stream.pullIf();
+        }
+    }
+
+    return stream;
+}
+
+pub fn destructor(self: *ReadableStream) void {
+    if (self.reader_resolver) |*rr| {
+        rr.deinit();
+    }
+}
+
+pub fn get_locked(self: *const ReadableStream) bool {
+    return self.locked;
+}
+
+pub fn _cancel(self: *ReadableStream, reason: ?[]const u8, page: *Page) !Env.Promise {
+    if (self.locked) {
+        return error.TypeError;
+    }
+
+    self.state = .{ .cancelled = if (reason) |r| try page.arena.dupe(u8, r) else null };
+
+    // Call cancel callback.
+    if (self.cancel_fn) |cancel| {
+        if (reason) |r| {
+            try cancel.call(void, .{r});
+        } else {
+            try cancel.call(void, .{});
+        }
+    }
+
+    try self.cancel_resolver.resolve({});
+    return self.cancel_resolver.promise();
+}
+
+pub fn pullIf(self: *ReadableStream) !void {
+    if (self.pull_fn) |pull_fn| {
+        // Must be under the high water mark AND readable.
+        if ((self.queue.items.len < self.strategy.high_water_mark) and self.state == .readable) {
+            const controller = ReadableStreamDefaultController{ .stream = self };
+            try pull_fn.call(void, .{controller});
+        }
+    }
+}
+
+const GetReaderOptions = struct {
+    // Mode must equal 'byob' or be undefined. RangeError otherwise.
+    mode: ?[]const u8 = null,
+};
+
+pub fn _getReader(self: *ReadableStream, _options: ?GetReaderOptions) !ReadableStreamDefaultReader {
+    if (self.locked) {
+        return error.TypeError;
+    }
+
+    // TODO: Determine if we need the ReadableStreamBYOBReader
+    const options = _options orelse GetReaderOptions{};
+    _ = options;
+
+    return ReadableStreamDefaultReader.constructor(self);
+}
+
+// TODO: pipeThrough (requires TransformStream)
+
+// TODO: pipeTo (requires WritableStream)
+
+// TODO: tee
+
+const testing = @import("../../testing.zig");
+test "streams: ReadableStream" {
+    try testing.htmlRunner("streams/readable_stream.html");
+}
diff --git a/src/browser/streams/ReadableStreamDefaultController.zig b/src/browser/streams/ReadableStreamDefaultController.zig
new file mode 100644
index 000000000..c83a13a57
--- /dev/null
+++ b/src/browser/streams/ReadableStreamDefaultController.zig
@@ -0,0 +1,82 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../../log.zig");
+
+const Page = @import("../page.zig").Page;
+const Env = @import("../env.zig").Env;
+
+const ReadableStream = @import("./ReadableStream.zig");
+const ReadableStreamReadResult = @import("./ReadableStream.zig").ReadableStreamReadResult;
+
+const ReadableStreamDefaultController = @This();
+
+stream: *ReadableStream,
+
+pub fn get_desiredSize(self: *const ReadableStreamDefaultController) i32 {
+    // TODO: This may need tuning at some point if it becomes a performance issue.
+    return @intCast(self.stream.queue.capacity - self.stream.queue.items.len);
+}
+
+pub fn _close(self: *ReadableStreamDefaultController, _reason: ?[]const u8, page: *Page) !void {
+    const reason = if (_reason) |reason| try page.arena.dupe(u8, reason) else null;
+    self.stream.state = .{ .closed = reason };
+
+    // Resolve the Reader Promise
+    if (self.stream.reader_resolver) |*rr| {
+        defer rr.deinit();
+        try rr.resolve(ReadableStreamReadResult{ .value = .empty, .done = true });
+        self.stream.reader_resolver = null;
+    }
+
+    // Resolve the Closed promise.
+    try self.stream.closed_resolver.resolve({});
+
+    // close just sets as closed meaning it wont READ any more but anything in the queue is fine to read.
+    // to discard, must use cancel.
+}
+
+pub fn _enqueue(self: *ReadableStreamDefaultController, chunk: []const u8, page: *Page) !void {
+    const stream = self.stream;
+
+    if (stream.state != .readable) {
+        return error.TypeError;
+    }
+
+    const duped_chunk = try page.arena.dupe(u8, chunk);
+
+    if (self.stream.reader_resolver) |*rr| {
+        defer rr.deinit();
+        try rr.resolve(ReadableStreamReadResult{ .value = .{ .data = duped_chunk }, .done = false });
+        self.stream.reader_resolver = null;
+    }
+
+    try self.stream.queue.append(page.arena, duped_chunk);
+    try self.stream.pullIf();
+}
+
+pub fn _error(self: *ReadableStreamDefaultController, err: Env.JsObject) !void {
+    self.stream.state = .{ .errored = err };
+
+    if (self.stream.reader_resolver) |*rr| {
+        defer rr.deinit();
+        try rr.reject(err);
+        self.stream.reader_resolver = null;
+    }
+}
diff --git a/src/browser/streams/ReadableStreamDefaultReader.zig b/src/browser/streams/ReadableStreamDefaultReader.zig
new file mode 100644
index 000000000..bf40e4dfa
--- /dev/null
+++ b/src/browser/streams/ReadableStreamDefaultReader.zig
@@ -0,0 +1,96 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+
+const log = @import("../../log.zig");
+const Env = @import("../env.zig").Env;
+const Page = @import("../page.zig").Page;
+const ReadableStream = @import("./ReadableStream.zig");
+const ReadableStreamReadResult = @import("./ReadableStream.zig").ReadableStreamReadResult;
+
+const ReadableStreamDefaultReader = @This();
+
+stream: *ReadableStream,
+
+pub fn constructor(stream: *ReadableStream) ReadableStreamDefaultReader {
+    return .{ .stream = stream };
+}
+
+pub fn get_closed(self: *const ReadableStreamDefaultReader) Env.Promise {
+    return self.stream.closed_resolver.promise();
+}
+
+pub fn _cancel(self: *ReadableStreamDefaultReader, reason: ?[]const u8, page: *Page) !Env.Promise {
+    return try self.stream._cancel(reason, page);
+}
+
+pub fn _read(self: *const ReadableStreamDefaultReader, page: *Page) !Env.Promise {
+    const stream = self.stream;
+
+    switch (stream.state) {
+        .readable => {
+            if (stream.queue.items.len > 0) {
+                const data = self.stream.queue.orderedRemove(0);
+                const resolver = page.main_context.createPromiseResolver();
+
+                try resolver.resolve(ReadableStreamReadResult{ .value = .{ .data = data }, .done = false });
+                try self.stream.pullIf();
+                return resolver.promise();
+            } else {
+                if (self.stream.reader_resolver) |rr| {
+                    return rr.promise();
+                } else {
+                    const persistent_resolver = try page.main_context.createPersistentPromiseResolver();
+                    self.stream.reader_resolver = persistent_resolver;
+                    return persistent_resolver.promise();
+                }
+            }
+        },
+        .closed => |_| {
+            const resolver = page.main_context.createPromiseResolver();
+
+            if (stream.queue.items.len > 0) {
+                const data = self.stream.queue.orderedRemove(0);
+                try resolver.resolve(ReadableStreamReadResult{ .value = .{ .data = data }, .done = false });
+            } else {
+                try resolver.resolve(ReadableStreamReadResult{ .value = .empty, .done = true });
+            }
+
+            return resolver.promise();
+        },
+        .cancelled => |_| {
+            const resolver = page.main_context.createPromiseResolver();
+            try resolver.resolve(ReadableStreamReadResult{ .value = .empty, .done = true });
+            return resolver.promise();
+        },
+        .errored => |err| {
+            const resolver = page.main_context.createPromiseResolver();
+            try resolver.reject(err);
+            return resolver.promise();
+        },
+    }
+}
+
+pub fn _releaseLock(self: *const ReadableStreamDefaultReader) !void {
+    self.stream.locked = false;
+
+    if (self.stream.reader_resolver) |rr| {
+        try rr.reject("TypeError");
+    }
+}
diff --git a/src/browser/streams/streams.zig b/src/browser/streams/streams.zig
new file mode 100644
index 000000000..f345640fb
--- /dev/null
+++ b/src/browser/streams/streams.zig
@@ -0,0 +1,24 @@
+// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+pub const Interfaces = .{
+    @import("ReadableStream.zig"),
+    @import("ReadableStream.zig").ReadableStreamReadResult,
+    @import("ReadableStreamDefaultReader.zig"),
+    @import("ReadableStreamDefaultController.zig"),
+};
diff --git a/src/cdp/domains/fetch.zig b/src/cdp/domains/fetch.zig
index ea7d225ab..f6fb302b9 100644
--- a/src/cdp/domains/fetch.zig
+++ b/src/cdp/domains/fetch.zig
@@ -200,6 +200,7 @@ pub fn requestIntercept(arena: Allocator, bc: anytype, intercept: *const Notific
             .script => "Script",
             .xhr => "XHR",
             .document => "Document",
+            .fetch => "Fetch",
         },
         .networkId = try std.fmt.allocPrint(arena, "REQ-{d}", .{transfer.id}),
     }, .{ .session_id = session_id });
@@ -405,6 +406,7 @@ pub fn requestAuthRequired(arena: Allocator, bc: anytype, intercept: *const Noti
             .script => "Script",
             .xhr => "XHR",
             .document => "Document",
+            .fetch => "Fetch",
         },
         .authChallenge = .{
             .source = if (challenge.source == .server) "Server" else "Proxy",
diff --git a/src/http/Client.zig b/src/http/Client.zig
index 11e8512dc..07a33390b 100644
--- a/src/http/Client.zig
+++ b/src/http/Client.zig
@@ -649,6 +649,7 @@ pub const Request = struct {
         document,
         xhr,
         script,
+        fetch,
     };
 };
 
diff --git a/src/http/Http.zig b/src/http/Http.zig
index 21b884693..949503b87 100644
--- a/src/http/Http.zig
+++ b/src/http/Http.zig
@@ -339,13 +339,13 @@ pub const Opts = struct {
     proxy_bearer_token: ?[:0]const u8 = null,
 };
 
-pub const Method = enum {
-    GET,
-    PUT,
-    POST,
-    DELETE,
-    HEAD,
-    OPTIONS,
+pub const Method = enum(u8) {
+    GET = 0,
+    PUT = 1,
+    POST = 2,
+    DELETE = 3,
+    HEAD = 4,
+    OPTIONS = 5,
 };
 
 // TODO: on BSD / Linux, we could just read the PEM file directly.
diff --git a/src/log.zig b/src/log.zig
index 24ae9ff89..d6e429fe3 100644
--- a/src/log.zig
+++ b/src/log.zig
@@ -39,6 +39,7 @@ pub const Scope = enum {
     unknown_prop,
     web_api,
     xhr,
+    fetch,
     polyfill,
     mouse_event,
 };
diff --git a/src/runtime/js.zig b/src/runtime/js.zig
index dbbc26a21..a486fc35a 100644
--- a/src/runtime/js.zig
+++ b/src/runtime/js.zig
@@ -677,6 +677,9 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             // we now simply persist every time persist() is called.
             js_object_list: std.ArrayListUnmanaged(PersistentObject) = .empty,
 
+
+            persisted_promise_resolvers: std.ArrayListUnmanaged(v8.Persistent(v8.PromiseResolver)) = .empty,
+
             // When we need to load a resource (i.e. an external script), we call
             // this function to get the source. This is always a reference to the
             // Page's fetchModuleSource, but we use a function pointer
@@ -733,6 +736,10 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     p.deinit();
                 }
 
+                for (self.persisted_promise_resolvers.items) |*p| {
+                    p.deinit();
+                }
+
                 {
                     var it = self.module_cache.valueIterator();
                     while (it.next()) |p| {
@@ -1130,6 +1137,16 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                         },
                         else => {},
                     },
+                    .array => |arr| {
+                        // Retrieve fixed-size array as slice
+                        const slice_type = []arr.child;
+                        const slice_value = try self.jsValueToZig(named_function, slice_type, js_value);
+                        if (slice_value.len != arr.len) {
+                            // Exact length match, we could allow smaller arrays, but we would not be able to communicate how many were written
+                            return error.InvalidArgument;
+                        }
+                        return @as(*T, @ptrCast(slice_value.ptr)).*;
+                    },
                     .@"struct" => {
                         return try (self.jsValueToStruct(named_function, T, js_value)) orelse {
                             return error.InvalidArgument;
@@ -1251,6 +1268,15 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 };
             }
 
+            pub fn createPersistentPromiseResolver(self: *JsContext) !PersistentPromiseResolver {
+                const resolver = v8.Persistent(v8.PromiseResolver).init(self.isolate, v8.PromiseResolver.init(self.v8_context));
+                try self.persisted_promise_resolvers.append(self.context_arena, resolver);
+                return .{
+                    .js_context = self,
+                    .resolver = resolver,
+                };
+            }
+
             // Probing is part of trying to map a JS value to a Zig union. There's
             // a lot of ambiguity in this process, in part because some JS values
             // can almost always be coerced. For example, anything can be coerced
@@ -1413,6 +1439,36 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                         },
                         else => {},
                     },
+                    .array => |arr| {
+                        // Retrieve fixed-size array as slice then probe
+                        const slice_type = []arr.child;
+                        switch (try self.probeJsValueToZig(named_function, slice_type, js_value)) {
+                            .value => |slice_value| {
+                                if (slice_value.len == arr.len) {
+                                    return .{ .value = @as(*T, @ptrCast(slice_value.ptr)).* };
+                                }
+                                return .{ .invalid = {} };
+                            },
+                            .ok => {
+                                // Exact length match, we could allow smaller arrays as .compatible, but we would not be able to communicate how many were written
+                                if (js_value.isArray()) {
+                                    const js_arr = js_value.castTo(v8.Array);
+                                    if (js_arr.length() == arr.len) {
+                                        return .{ .ok = {} };
+                                    }
+                                } else if (js_value.isString() and arr.child == u8) {
+                                    const str = try js_value.toString(self.v8_context);
+                                    if (str.lenUtf8(self.isolate) == arr.len) {
+                                        return .{ .ok = {} };
+                                    }
+                                }
+                                return .{ .invalid = {} };
+                            },
+                            .compatible => return .{ .compatible = {} },
+                            .coerce => return .{ .coerce = {} },
+                            .invalid => return .{ .invalid = {} },
+                        }
+                    },
                     .@"struct" => {
                         // We don't want to duplicate the code for this, so we call
                         // the actual conversion function.
@@ -2178,6 +2234,54 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     return error.FailedToResolvePromise;
                 }
             }
+
+            pub fn reject(self: PromiseResolver, value: anytype) !void {
+                const js_context = self.js_context;
+                const js_value = try js_context.zigValueToJs(value);
+
+                // resolver.reject will return null if the promise isn't pending
+                const ok = self.resolver.reject(js_context.v8_context, js_value) orelse return;
+                if (!ok) {
+                    return error.FailedToRejectPromise;
+                }
+            }
+        };
+
+        pub const PersistentPromiseResolver = struct {
+            js_context: *JsContext,
+            resolver: v8.Persistent(v8.PromiseResolver),
+
+            pub fn deinit(self: *PersistentPromiseResolver) void {
+                self.resolver.deinit();
+            }
+
+            pub fn promise(self: PersistentPromiseResolver) Promise {
+                return .{
+                    .promise = self.resolver.castToPromiseResolver().getPromise(),
+                };
+            }
+
+            pub fn resolve(self: PersistentPromiseResolver, value: anytype) !void {
+                const js_context = self.js_context;
+                const js_value = try js_context.zigValueToJs(value);
+
+                // resolver.resolve will return null if the promise isn't pending
+                const ok = self.resolver.castToPromiseResolver().resolve(js_context.v8_context, js_value) orelse return;
+                if (!ok) {
+                    return error.FailedToResolvePromise;
+                }
+            }
+
+            pub fn reject(self: PersistentPromiseResolver, value: anytype) !void {
+                const js_context = self.js_context;
+                const js_value = try js_context.zigValueToJs(value);
+
+                // resolver.reject will return null if the promise isn't pending
+                const ok = self.resolver.castToPromiseResolver().reject(js_context.v8_context, js_value) orelse return;
+                if (!ok) {
+                    return error.FailedToRejectPromise;
+                }
+            }
         };
 
         pub const Promise = struct {
diff --git a/src/tests/fetch/fetch.html b/src/tests/fetch/fetch.html
new file mode 100644
index 000000000..8b4019d49
--- /dev/null
+++ b/src/tests/fetch/fetch.html
@@ -0,0 +1,16 @@
+<script src="https://github.com/testing.js"></script>
+<script id=fetch type=module>
+  const promise1 = new Promise((resolve) => {
+    fetch('https://github.com/service/http://127.0.0.1:9582/xhr/json')
+    .then((res) => {
+      return res.json()
+    })
+    .then((json) => {
+      resolve(json);
+    });
+  });
+
+  testing.async(promise1, (json) => {
+    testing.expectEqual({over: '9000!!!'}, json);
+  });
+</script>
diff --git a/src/tests/fetch/headers.html b/src/tests/fetch/headers.html
new file mode 100644
index 000000000..57d6ce2ee
--- /dev/null
+++ b/src/tests/fetch/headers.html
@@ -0,0 +1,102 @@
+<script src="https://github.com/testing.js"></script>
+
+<script id=headers>
+  let headers = new Headers({"Set-Cookie": "name=world"});
+  testing.expectEqual("name=world", headers.get("set-cookie"));
+
+  let myHeaders = new Headers();
+  myHeaders.append("Content-Type", "image/jpeg"),
+  testing.expectEqual(false, myHeaders.has("Picture-Type"));
+  testing.expectEqual("image/jpeg", myHeaders.get("Content-Type"));
+
+  myHeaders.append("Content-Type", "image/png");
+  testing.expectEqual("image/jpeg, image/png", myHeaders.get("Content-Type"));
+
+  myHeaders.delete("Content-Type");
+  testing.expectEqual(null, myHeaders.get("Content-Type"));
+
+  myHeaders.set("Picture-Type", "image/svg")
+  testing.expectEqual("image/svg", myHeaders.get("Picture-Type"));
+  testing.expectEqual(true, myHeaders.has("Picture-Type"))
+
+  const originalHeaders = new Headers([["Content-Type", "application/json"], ["Authorization", "Bearer token123"]]);
+  testing.expectEqual("application/json", originalHeaders.get("Content-Type"));
+  testing.expectEqual("Bearer token123", originalHeaders.get("Authorization"));
+
+  const newHeaders = new Headers(originalHeaders);
+  testing.expectEqual("application/json", newHeaders.get("Content-Type"));
+  testing.expectEqual("Bearer token123" ,newHeaders.get("Authorization"));
+  testing.expectEqual(true ,newHeaders.has("Content-Type"));
+  testing.expectEqual(true ,newHeaders.has("Authorization"));
+  testing.expectEqual(false, newHeaders.has("X-Custom"));
+
+  newHeaders.set("X-Custom", "test-value");
+  testing.expectEqual("test-value", newHeaders.get("X-Custom"));
+  testing.expectEqual(null, originalHeaders.get("X-Custom"));
+  testing.expectEqual(false, originalHeaders.has("X-Custom"));
+</script>
+
+<script id=keys>
+  const testKeyHeaders = new Headers();
+  testKeyHeaders.set("Content-Type", "application/json");
+  testKeyHeaders.set("Authorization", "Bearer token123");
+  testKeyHeaders.set("X-Custom", "test-value");
+
+  const keys = [];
+  for (const key of testKeyHeaders.keys()) {
+      keys.push(key);
+  }
+
+  testing.expectEqual(3, keys.length);
+  testing.expectEqual(true, keys.includes("Content-Type"));
+  testing.expectEqual(true, keys.includes("Authorization"));
+  testing.expectEqual(true, keys.includes("X-Custom"));
+</script>
+
+<script id=values>
+  const testValuesHeaders = new Headers();
+  testValuesHeaders.set("Content-Type", "application/json");
+  testValuesHeaders.set("Authorization", "Bearer token123");
+  testValuesHeaders.set("X-Custom", "test-value");
+
+  const values = [];
+  for (const value of testValuesHeaders.values()) {
+      values.push(value);
+  }
+
+  testing.expectEqual(3, values.length);
+  testing.expectEqual(true, values.includes("application/json"));
+  testing.expectEqual(true, values.includes("Bearer token123"));
+  testing.expectEqual(true, values.includes("test-value"));
+</script>
+
+<script id=entries>
+  const testEntriesHeaders = new Headers();
+  testEntriesHeaders.set("Content-Type", "application/json");
+  testEntriesHeaders.set("Authorization", "Bearer token123");
+  testEntriesHeaders.set("X-Custom", "test-value");
+
+  const entries = [];
+  for (const entry of testEntriesHeaders.entries()) {
+      entries.push(entry);
+  }
+        
+  testing.expectEqual(3, entries.length);
+
+  const entryMap = new Map(entries);
+  testing.expectEqual("application/json", entryMap.get("Content-Type"));
+  testing.expectEqual("Bearer token123", entryMap.get("Authorization"));
+  testing.expectEqual("test-value", entryMap.get("X-Custom"));
+  
+  const entryKeys = Array.from(entryMap.keys());
+  testing.expectEqual(3, entryKeys.length);
+  testing.expectEqual(true, entryKeys.includes("Content-Type"));
+  testing.expectEqual(true, entryKeys.includes("Authorization"));
+  testing.expectEqual(true, entryKeys.includes("X-Custom"));
+  
+  const entryValues = Array.from(entryMap.values());
+  testing.expectEqual(3, entryValues.length);
+  testing.expectEqual(true, entryValues.includes("application/json"));
+  testing.expectEqual(true, entryValues.includes("Bearer token123"));
+  testing.expectEqual(true, entryValues.includes("test-value"))
+</script>
diff --git a/src/tests/fetch/request.html b/src/tests/fetch/request.html
new file mode 100644
index 000000000..7bfdfe56e
--- /dev/null
+++ b/src/tests/fetch/request.html
@@ -0,0 +1,22 @@
+<script src="https://github.com/testing.js"></script>
+
+<script id=request>
+  let request = new Request("flower.png");
+  testing.expectEqual("http://localhost:9582/src/tests/fetch/flower.png", request.url);
+  testing.expectEqual("GET", request.method);
+
+  let request2 = new Request("https://google.com/", {
+    method: "POST",
+    body: "Hello, World",
+    cache: "reload",
+    credentials: "omit",
+    headers: { "Sender": "me", "Target": "you" }
+    }
+  );
+  testing.expectEqual("https://google.com/", request2.url);
+  testing.expectEqual("POST", request2.method);
+  testing.expectEqual("omit", request2.credentials);
+  testing.expectEqual("reload", request2.cache);
+  testing.expectEqual("me", request2.headers.get("SeNdEr"));
+  testing.expectEqual("you", request2.headers.get("target"));
+</script>
diff --git a/src/tests/fetch/response.html b/src/tests/fetch/response.html
new file mode 100644
index 000000000..01b4c8e72
--- /dev/null
+++ b/src/tests/fetch/response.html
@@ -0,0 +1,49 @@
+<script src="https://github.com/testing.js"></script>
+
+<script id=response>
+  let response = new Response("Hello, World!");
+  testing.expectEqual(200, response.status);
+  testing.expectEqual("", response.statusText);
+  testing.expectEqual(true, response.ok);
+  testing.expectEqual("", response.url);
+  testing.expectEqual(false, response.redirected);
+
+  let response2 = new Response("Error occurred", {
+    status: 404,
+    statusText: "Not Found",
+    headers: { 
+        "Content-Type": "text/plain", 
+        "X-Custom": "test-value",
+        "Cache-Control": "no-cache"
+    }
+  });
+  testing.expectEqual(404, response2.status);
+  testing.expectEqual("Not Found", response2.statusText);
+  testing.expectEqual(false, response2.ok);
+  testing.expectEqual("text/plain", response2.headers.get("Content-Type"));
+  testing.expectEqual("test-value", response2.headers.get("X-Custom"));
+  testing.expectEqual("no-cache", response2.headers.get("cache-control"));
+        
+  let response3 = new Response("Created", { status: 201, statusText: "Created" });
+  testing.expectEqual(201, response3.status);
+  testing.expectEqual("Created", response3.statusText);
+  testing.expectEqual(true, response3.ok);
+
+  let nullResponse = new Response(null);
+  testing.expectEqual(200, nullResponse.status);
+  testing.expectEqual("", nullResponse.statusText);
+
+  let emptyResponse = new Response("");
+  testing.expectEqual(200, emptyResponse.status);
+</script>
+
+<script id=json type=module>
+  const promise1 = new Promise((resolve) => {
+    let response = new Response('[]');
+    response.json().then(resolve)
+  });
+
+  testing.async(promise1, (json) => {
+    testing.expectEqual([], json);
+  });
+</script>
diff --git a/src/tests/html/html_slot_element.html b/src/tests/html/html_slot_element.html
new file mode 100644
index 000000000..058b67853
--- /dev/null
+++ b/src/tests/html/html_slot_element.html
@@ -0,0 +1,66 @@
+<script src="https://github.com/testing.js"></script>
+<script>
+  class LightPanda extends HTMLElement {
+    constructor() {
+      super();
+    }
+
+    connectedCallback() {
+      const shadow = this.attachShadow({ mode: "open" });
+
+      const slot1 = document.createElement('slot');
+      slot1.name = 'slot-1';
+      shadow.appendChild(slot1);
+
+      switch (this.getAttribute('mode')) {
+        case '1':
+          slot1.innerHTML = 'hello';
+          break;
+        case '2':
+          const slot2 = document.createElement('slot');
+          shadow.appendChild(slot2);
+          break;
+      }
+    }
+  }
+  window.customElements.define("lp-test", LightPanda);
+</script>
+
+<lp-test id=lp1 mode=1></lp-test>
+<lp-test id=lp2 mode=0></lp-test>
+<lp-test id=lp3 mode=0>default</lp-test>
+<lp-test id=lp4 mode=1><p slot=other>default</p></lp-test>
+<lp-test id=lp5 mode=1><p slot=slot-1>default</p> xx <b slot=slot-1>other</b></lp-test>
+<lp-test id=lp6 mode=2>More <p slot=slot-1>default2</p> <span>!!</span></lp-test>
+
+<script id=HTMLSlotElement>
+  function assertNodes(expected, actual) {
+    actual = actual.map((n) => n.id || n.textContent)
+    testing.expectEqual(expected, actual);
+  }
+
+  for (let idx of [1, 2, 3, 4]) {
+    const lp = $(`#lp${idx}`);
+    const slot = lp.shadowRoot.querySelector('slot');
+
+    assertNodes([], slot.assignedNodes());
+    assertNodes([], slot.assignedNodes({}));
+    assertNodes([], slot.assignedNodes({flatten: false}));
+    if (lp.getAttribute('mode') === '1') {
+      assertNodes(['hello'], slot.assignedNodes({flatten: true}));
+    } else {
+      assertNodes([], slot.assignedNodes({flatten: true}));
+    }
+  }
+
+  const lp5 = $('#lp5');
+  const s5 = lp5.shadowRoot.querySelector('slot');
+  assertNodes(['default', 'other'], s5.assignedNodes());
+
+  const lp6 = $('#lp6');
+  const s6 = lp6.shadowRoot.querySelectorAll('slot');
+  assertNodes(['default2'], s6[0].assignedNodes({}));
+  assertNodes(['default2'], s6[0].assignedNodes({flatten: true}));
+  assertNodes(['More ', ' ', '!!'], s6[1].assignedNodes({}));
+  assertNodes(['More ', ' ', '!!'], s6[1].assignedNodes({flatten: true}));
+</script>
diff --git a/src/tests/streams/readable_stream.html b/src/tests/streams/readable_stream.html
new file mode 100644
index 000000000..a8d71d666
--- /dev/null
+++ b/src/tests/streams/readable_stream.html
@@ -0,0 +1,117 @@
+<script src="https://github.com/testing.js"></script>
+
+<script id=readable_stream>
+  const stream = new ReadableStream({
+    start(controller) {
+      controller.enqueue("hello");
+      controller.enqueue("world");
+      controller.close();
+    }
+  });
+
+  const reader = stream.getReader();
+
+  testing.async(reader.read(), (data) => {
+    testing.expectEqual("hello", data.value);
+    testing.expectEqual(false, data.done);
+  });
+</script>
+
+<script id=readable_stream_close>
+  var closeResult;
+
+  const stream1 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("first");
+      controller.enqueue("second");
+      controller.close();
+    }
+  });
+
+  const reader1 = stream1.getReader();
+
+  testing.async(reader1.read(), (data) => {
+    testing.expectEqual("first", data.value);
+    testing.expectEqual(false, data.done);
+  });
+
+  testing.async(reader1.read(), (data) => {
+    testing.expectEqual("second", data.value);
+    testing.expectEqual(false, data.done);
+  });
+
+  testing.async(reader1.read(), (data) => {
+    testing.expectEqual(undefined, data.value);
+    testing.expectEqual(true, data.done);
+  });
+</script>
+
+<script id=readable_stream_cancel>
+  var readResult;
+  var cancelResult;
+  var closeResult;
+
+  const stream2 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("data1");
+      controller.enqueue("data2");
+      controller.enqueue("data3");
+    },
+    cancel(reason) {
+      closeResult = `Stream cancelled: ${reason}`;
+    }
+  });
+
+  const reader2 = stream2.getReader();
+
+  testing.async(reader2.read(), (data) => {
+    testing.expectEqual("data1", data.value);
+    testing.expectEqual(false, data.done);
+  });
+
+  testing.async(reader2.cancel("user requested"), (result) => {
+    testing.expectEqual(undefined, result);
+    testing.expectEqual("Stream cancelled: user requested", closeResult);
+  });
+</script>
+
+<script id=readable_stream_cancel_no_reason>
+  var closeResult2;
+
+  const stream3 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("test");
+    },
+    cancel(reason) {
+      closeResult2 = reason === undefined ? "no reason" : reason;
+    }
+  });
+
+  const reader3 = stream3.getReader();
+
+  testing.async(reader3.cancel(), (result) => {
+    testing.expectEqual(undefined, result);
+    testing.expectEqual("no reason", closeResult2);
+  });
+</script>
+
+<script id=readable_stream_read_after_cancel>
+  var readAfterCancelResult;
+
+  const stream4 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("before_cancel");
+    },
+  });
+
+  const reader4 = stream4.getReader();
+
+  testing.async(reader4.cancel("test cancel"), (cancelResult) => {
+    testing.expectEqual(undefined, cancelResult);
+  });
+
+  testing.async(reader4.read(), (data) => {
+    testing.expectEqual(undefined, data.value);
+    testing.expectEqual(true, data.done);
+  });
+</script>