Developer Tools

by Zulkarnain K.

50 Add-ons in this Collection

Firebug by Joe Hewitt, Jan Odvarko, others

Rated 4 out of 5 stars 2,121 reviews

1,334,098 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 userstyles.org

Rated 4 out of 5 stars 895 reviews

350,297 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 278 reviews

298,826 users

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

Tamper Data by Adam Judson

Rated 4 out of 5 stars 174 reviews

63,170 users

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

SQLite Manager by lazierthanthou

Rated 4 out of 5 stars 83 reviews

143,155 users

Manage any SQLite database on your computer.

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

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 4 out of 5 stars 387 reviews

171,632 users

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

Lightbeam for Firefox by Mozilla

Rated 4 out of 5 stars 446 reviews

243,488 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.

JSONView by Ben Hollis

Rated 5 out of 5 stars 177 reviews

85,294 users

View JSON documents in the browser.

JavaScript Deobfuscator by Wladimir Palant

Rated 4 out of 5 stars 26 reviews

31,941 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.

HttpFox by Martin Theimer

Rated 4 out of 5 stars 173 reviews

53,638 users

An HTTP analyzer addon for Firefox

Live HTTP Headers by Daniel Savard, Nikolas Co

Rated 4 out of 5 stars 177 reviews

86,058 users

View HTTP headers of a page and while browsing.

Remote XUL Manager by Jorge Villalobos

Rated 5 out of 5 stars 34 reviews

87,023 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

Download Now

Experimental

Rated 4 out of 5 stars 136 reviews

18,050 users

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

DOM Inspector by SeaMonkey Council

Rated 5 out of 5 stars 75 reviews

72,724 users

DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.
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