Developer Tools

by Zulkarnain K.

51 Add-ons in this Collection

Firebug by Joe Hewitt, Jan Odvarko, others

Rated 5 out of 5 stars 1,807 reviews

2,279,729 users

Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page...

Stylish by Jason Barnabe

Rated 4 out of 5 stars 785 reviews

528,428 users

Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Tumblr, and many, many other sites. You can even customize Firefox and other programs themselves.

Web Developer by chrispederick

Rated 5 out of 5 stars 221 reviews

538,328 users

The Web Developer extension adds various web developer tools to the browser.

SQLite Manager by lazierthanthou

Rated 5 out of 5 stars 43 reviews

204,995 users

Manage any SQLite database on your computer.

Tamper Data by Adam Judson

Rated 4 out of 5 stars 134 reviews

113,687 users

Use tamperdata to view and modify HTTP/HTTPS headers and post parameters...

Lightbeam for Firefox by Mozilla

Rated 4 out of 5 stars 410 reviews

593,257 users

Lightbeam is a Firefox add-on that enables you to see the first and third party sites you interact with on the Web. Using interactive visualizations, Lightbeam shows you the relationships between these third parties and the sites you visit.

JavaScript Debugger by James Ross, Robert Ginda, others

Rated 4 out of 5 stars 50 reviews

126,137 users

As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.

Venkman is the code name for Mozilla's JavaScript Debugger. Venkman aimed to provide a powerful JavaScript debugging environment for Mozilla based browsers.

RESTClient, a debugger for RESTful web services. by Chao ZHOU

Rated 4 out of 5 stars 84 reviews

147,981 users

Notice: some important features (XML indentation and load old saved requests) are missing in version 2.0.0, please update to version 2.0.1.

Please follow the link ("View other versions") below To install version 2.0.1.

ColorZilla by Alex Sirota

Rated 5 out of 5 stars 306 reviews

288,431 users

Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...

Live HTTP Headers by Daniel Savard, Nikolas Co

Rated 4 out of 5 stars 164 reviews

166,238 users

View HTTP headers of a page and while browsing.

JSONView by Ben Hollis

Rated 5 out of 5 stars 141 reviews

108,258 users

View JSON documents in the browser.

HttpFox by Martin Theimer

Rated 4 out of 5 stars 166 reviews

96,510 users

An HTTP analyzer addon for Firefox

JavaScript Deobfuscator by Wladimir Palant

Rated 5 out of 5 stars 19 reviews

59,167 users

This add-on shows you what JavaScript code runs on a web page, even if it is obfuscated and generated on the fly. Simply open JavaScript Deobfuscator from the Web Developer menu and watch the scripts being compiled/executed.

Remote XUL Manager by Jorge Villalobos

Rated 5 out of 5 stars 36 reviews

73,373 users

Manages the Remote XUL whitelist to allow websites and local files to load XUL content. For versions compatible with Firefox 41 and lower, see All Versions page below.

about:addons-memory by Nils Maier

Adds an about:addons-memory page that details add-on memory usage
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