Here we go: my current favorites, respectively sometimes used addons. Don’t know them? Just try ‘em.
Testing & debugging
- Firebug – still THE reference
- Pingr – link checker
- Firefox Accessibility Extension
- HTML Validator – either TIDY or SGML check
- Selenium IDE – form validation, automated process testing
- Web Developer
Measure & evaluate
- Colorzilla – Measure colors and much more
- Live HTTP headers
- MeasureIt – replaced with measuring tools in the Web Developer Toolbar
- ShowIP
- WASP – for tracking purposes
Development
- CSS Reloader – reload css only simply by hitting F9. Big impact on large sites
- Firefinder
- Fireshot – screenshot tool of choice. Captures whole Web pages, too.
- “Firequery”: – extremely useful addon when using jQuery. Shows events on elements in firebug’s html view.
- Flashblock
- Pixel Perfect – put an onion layer of layout on your website
- Prefbar – switch preferences with one click, such as JS or Flash on/off.
- Profile Manager and Synchronizer – might be useful, not in use currently
Customizing
Performance testing
Communications
Else
- FireFTP – browser-based FTP client