Web Development

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Microsoft .NET Framework Assistant

Adds ClickOnce support and the ability to report installed .NET versions to the web server.

Rated 2 out of 5 stars (116)
10,388 weekly downloads

Live HTTP Headers

View HTTP headers of a page and while browsing.

Rated 4 out of 5 stars (136)
9,485 weekly downloads

JavaScript Debugger

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

Rated 4 out of 5 stars (47)
8,693 weekly downloads

ColorfulTabs Featured

The most beautiful yet the simplest add-on that makes a strong colorful appeal. Colors every tab in a different color and makes them easy to distinguish while beautifying the overall appearance of the interface. For Seamonkey & Flock. An essential. F...

Rated 4 out of 5 stars (863)
8,682 weekly downloads

RESTClient, a debugger for RESTful web services.

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.

Rated 4 out of 5 stars (67)
8,662 weekly downloads

The Addon Bar (Restored) No Restart

Gives you a place to put all your add-on buttons without over-crowding the navigation bar.

Rated 5 out of 5 stars (185)
8,432 weekly downloads

Firefox OS 1.1 Simulator No Restart

Firefox OS Simulator is a test environment for Firefox OS. Use it to test your apps in a Firefox OS-like environment that looks and feels like a mobile phone. After installing it, go to Web Developer > Firefox OS Simulator to access its features.

Rated 4 out of 5 stars (56)
7,666 weekly downloads

HttpFox

An HTTP analyzer addon for Firefox

Rated 4 out of 5 stars (154)
7,478 weekly downloads

Cookies Manager+

Cookies manager to view, edit and create new cookies. It also shows extra information about cookies, allows edit multiple cookies at once and backup/restore them.

Rated 4 out of 5 stars (60)
6,973 weekly downloads

MeasureIt

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

Rated 4 out of 5 stars (305)
6,920 weekly downloads

RDS bar (seo: pr, dmoz, alexa, seomoz)

RDS seo toolbar (pr, dmoz, alexa, seomoz ... ) – is a useful tool for fast analysis of website and page SEO indicators, designed for webmasters and optimizers. And also with a range of useful functions for ordinary users.

Rated 4 out of 5 stars (33)
6,625 weekly downloads

YSlow

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

Rated 3 out of 5 stars (167)
6,559 weekly downloads

Fire IE (FireIE, Enhanced IE)

Embeds Internet Explorer(IE) to use the powerful Firefox add-ons.
Not only an enhanced IE Tab, but also an enhanced Internet Explorer with Adblock Plus and FireGestures support.
Switch to the IE engine in one click and dismiss your IE.

Rated 4 out of 5 stars (98)
6,500 weekly downloads

Screengrab (fix version)

Screengrab! saves webpages as images.
0.97 released!
New features: upload to internet

Rated 5 out of 5 stars (162)
6,190 weekly downloads

User Agent Overrider No Restart

Override browser user agent string

Rated 4 out of 5 stars (25)
5,983 weekly downloads

Image Zoom

Adds zoom and rotation functionality for images...

Rated 4 out of 5 stars (310)
5,959 weekly downloads

Scriptish

The greatest user script engine on the Internet (a fork of Greasemonkey).

Rated 4 out of 5 stars (92)
5,895 weekly downloads

FirePath

FirePath is a Firebug extension that adds a development tool to edit, inspect and generate XPath 1.0 expressions, CSS 3 selectors and JQuery selectors (Sizzle selector engine).

Rated 4 out of 5 stars (16)
5,778 weekly downloads

One Click Proxy IP No Restart

The easiest way ever to change IP and browse anonymously! Just activate it with one click and it's done, you're browsing the web with a random HTTP or Socks proxy list from several countries in the world. No ads. 100% free to prevent web censorship.

Rated 4 out of 5 stars (15)
5,710 weekly downloads

Nimbus Screen Capture - editable screenshots No Restart

Screen capture Web Page, selected region or whole browser window, edit screenshots and save the images to Local File or Google Drive. Edit screenshots in a very user-friendly interface with the different tools.

Rated 5 out of 5 stars (47)
5,563 weekly downloads