Optional Authentication

🧠 Backend concept I learned today that changed how I design APIs:

👉 Optional Authentication

Most people think APIs are either:

❌ Public
❌ Protected

But there’s a third type 👀

🔥 Optional Auth:

✔ Anyone can access
✔ BUT if logged in → return extra data

📌 Example (coding platform):

GET /problems/:slug

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Logged out:
→ show problem + starter code

Logged in:
→ show problem + user’s saved code

💡 Same API, different experience

⚡ Why this is powerful:

✔ No multiple API calls
✔ Cleaner frontend
✔ Better UX
✔ Scales like real products

Used in:
LeetCode, GitHub, Twitter, Notion 👀

🧠 Key idea:

“Don’t block users — enhance experience if they are logged in”

This one concept made my backend feel 10x cleaner 😤

Example —

export const optionalAuth = (req, res, next) => {
  try {
    const token = req.cookies.token;
    if (token) {
      const decoded = jwt.verify(token, process.env.JWT_SECRET);
      req.user = decoded;
    }
  } catch (err) {
    // intentionally empty
  }
  next();
};