Pro Developer

by JamesWilson

37 Add-ons in this Collection

Adblock Plus by Wladimir Palant

Rated 5 out of 5 stars 4,888 reviews

20,704,696 users

Blocks annoying video ads on YouTube, Facebook ads, banners and much more.

Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).

Firebug by Joe Hewitt, Jan Odvarko, others

Rated 5 out of 5 stars 1,840 reviews

2,114,296 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...

Greasemonkey by Anthony Lieuallen, Aaron Boodman, others

Rated 4 out of 5 stars 1,012 reviews

1,254,753 users

Customize the way a web page displays or behaves, by using small bits of JavaScript.

DownThemAll! by Nils Maier, Federico Parodi, others

Rated 4 out of 5 stars 1,805 reviews

1,260,021 users

The first and only download manager/accelerator built inside Firefox!

FoxyProxy Standard by Eric H. Jung, groeg, others

Rated 4 out of 5 stars 363 reviews

274,484 users

FoxyProxy is an advanced proxy management tool that completely replaces Firefox's limited proxying capabilities. For a simpler tool and less advanced configuration options, please use FoxyProxy Basic.

Web Developer by chrispederick

Rated 5 out of 5 stars 249 reviews

470,067 users

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

Full Web Page Screenshots (♥♥♥♥♥) by susbox

FireShot makes full web page screenshots. Demo:

Screenshots can be quickly captured and:

― Saved as Image or PDF
― Sent to clipboard
― Printed
― Annotated *
― Uploaded *
― E-Mailed *

* OS Windows only

Tamper Data by Adam Judson

Rated 4 out of 5 stars 142 reviews

104,451 users

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

ColorZilla by Alex Sirota

Rated 5 out of 5 stars 312 reviews

259,341 users

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

ReloadEvery by Jaap Haitsma

Rated 4 out of 5 stars 715 reviews

156,487 users

Reloads web pages every so many seconds or minutes. The function is accessible via the context menu (menu you get when you right click on a web page) or via tab context menu (right click on the tab)

Live HTTP Headers by Daniel Savard, Nikolas Co

Rated 4 out of 5 stars 170 reviews

144,551 users

View HTTP headers of a page and while browsing.

JavaScript Debugger by James Ross, Robert Ginda, others

Rated 4 out of 5 stars 49 reviews

113,378 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.

MeasureIt by Kevin Freitas

Rated 4 out of 5 stars 358 reviews

137,188 users

Draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.

ColorfulTabs by Shivanand Sharma

Rated 4 out of 5 stars 1,014 reviews

236,800 users

The first addon you should be installing on a fresh Firefox install. A must have. The most beautiful yet the simplest add-on that makes a strong colorful appeal. Colors every tab in a different color.

YSlow by YSlow

Rated 3 out of 5 stars 215 reviews

76,097 users

YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages. is the official open source website.
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