Update README.md

Author: TheMuellenator

README.md

@@ -114,6 +114,11 @@
 * [HTTP Package API Reference](https://pub.dartlang.org/documentation/http/latest/)
 * [HTTP Response Class Documentation](https://pub.dartlang.org/documentation/http/latest/http/Response-class.html)
 * [List of HTTP Status Codes](https://www.restapitutorial.com/httpstatuscodes.html)
+* [Chrome Plugin for Formatting and Viewing JSON](https://chrome.google.com/webstore/detail/json-viewer-awesome/iemadiahhbebdklepanmkjenfdebfpfe?hl=en)
+* [JSON Mate: Formatting and Viewing JSON without a plugin](http://jsonmate.com/)
+* [Loading Indicators from the Flutter Spinkit](https://pub.dartlang.org/packages/flutter_spinkit)
+* [The State Class](https://docs.flutter.io/flutter/widgets/State-class.html)
+