Article : Useful Extensions for Firefox Extension Developers

• Extension Developer's Extension
  The Extension Developer's Extension exists to make life easier for Firefox extension developers. Testing JavaScript code, prototyping XUL layouts, and building XPI packages are all made easier by this extension.

Features are :

1. Extension Builder

2. Install.rdf Editor

3. Javascript Shell ( Try it online! )

4. Javascript Environment (Try it online! )

5. Live XUL Editor (Try it online! )

6. Live HTML Editor (Try it online! )

7. JRX: real-time JavaScript RegExp evaluator (Try it online! )

8. Interactive XPath Tester (Try the original online! )

9. Enable Debugging Prefs

• ChromeBug (FireBug)