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Live HTTP Headers Requires Restart

View HTTP headers of a page and while browsing.

Rated 4 out of 5 stars (215)
86,801 users

RefControl Requires Restart

Control what gets sent as the HTTP Referer on a per-site basis.

Rated 4 out of 5 stars (180)
56,425 users

MR Tech Toolkit Requires Restart

(Formerly Local Install) The primary goal of this extension is to provide the tools needed to install and manage extensions and themes locally and tons of other features.

Note: With Toolkit 6.0 Auto Archiving is fully working in Firefox 2.0 and temp...

Rated 4 out of 5 stars (134)
6,156 users

Scriptish Requires Restart

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

Rated 4 out of 5 stars (109)
16,518 users

jQuery Requires Restart

jQuery and jQuery UI embedded in browser

Rated 4 out of 5 stars (7)
1,627 users

Dafizilla Table2Clipboard Requires Restart

Mozilla applications allow to select rows and columns from a table simply pressing Control key and picking rows/columns with left mouse button.
The selection can be copied to clipboard but the original table disposition is lost making ugly results wh...

Rated 5 out of 5 stars (74)
10,703 users

Remote XUL Manager

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.

Rated 5 out of 5 stars (36)
102,228 users

IE Tab + (FF 8+, 7, 6, 5, 4, 3.6, 3.5, SeaMonkey) Requires Restart

IE Tab + is an enhanced version of IE Tab. It supports FF 3.5 or greater, integrates IE Tab with Adblock Plus in the IE Tab engine, and synchronizes cookies between IE and Firefox. You can easily import settings from the original IE Tab into IE Tab +

Rated 3 out of 5 stars (85)
27,235 users

Link Properties Plus Requires Restart

Provides extended link properties: size of linked file, last modified time, etc.

Rated 5 out of 5 stars (17)
1,063 users

JavaScript Debugger Requires Restart

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.

Rated 4 out of 5 stars (52)
60,294 users

PrefBar Requires Restart

The all in one toolbar(item). Houses and manages bigger amounts of buttons (Clear Cache, Clear Cookies, ...), Menus (User Agent spoof...) and checkboxes (Javascript, Flash, ...). Extensible from online-database or with self created buttons.

Rated 5 out of 5 stars (42)
9,592 users

Add-ons Manager - Version Number [Fx/Tb 45-56]

Restores version numbers for all installed add-ons inside Add-on Manager on Firefox, Thunderbird and Seamonkey.

Rated 5 out of 5 stars (28)
1,544 users

Firesizer Requires Restart

Allows you to resize the window to specific dimensions.

NOTE: Users of Firefox 29 and above must install "The Addon Bar" extension to use this, as Firesizer uses the add-on bar that has been removed in Firefox 29.

Rated 4 out of 5 stars (127)
11,300 users

Debugger Server Enabler

Starts the remote debugger server.

Not yet rated
3 users

Stylish-Custom Requires Restart

custom additions to Stylish extension

Rated 4 out of 5 stars (10)
1,039 users

MR Tech Disable XPI Install Delay Requires Restart

Disables default delay when installing...

Rated 5 out of 5 stars (16)
31 users

BrightSide XUL Installer

Automatically installs a set of domains to the Remote XUL whitelist.

Not yet rated
1 user

MR Tech About:About Requires Restart

Adds the following "about:" options to the Help menu

Rated 3 out of 5 stars (8)
24 users

Key Manager Requires Restart

KeyManager Tool: Firefox Add-on for Key Generation, Certificate Enrollment, CRL Signing, and Identity and Authority Delegation

Rated 3 out of 5 stars (21)
84 users

View Source Requires Restart

Shows all source files of a webpage.

Rated 4 out of 5 stars (7)
515 users