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Tamper Data Requires Restart Featured

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

Rated 4 out of 5 stars (140)
104,115 users

Webmail Ad Blocker Featured

Expand your email area by blocking and removing ads on the right hand side of the screen when using Gmail, Hotmail, Outlook.com and Yahoo Mail.

Rated 4 out of 5 stars (203)
104,047 users

Cookies Manager+ Requires Restart

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 5 out of 5 stars (67)
102,898 users

Modify Headers Requires Restart

Add, modify and filter the HTTP request headers sent to web servers. This addon is particularly useful for Mobile web development, HTTP testing and privacy.

Rated 4 out of 5 stars (76)
102,851 users

Theme Font & Size Changer Featured

Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.

Rated 5 out of 5 stars (227)
100,152 users

Strict Pop-up Blocker

Quickly toggle between blocking all pop-up windows and allowing some pop-ups

Rated 4 out of 5 stars (86)
99,354 users

R-kiosk Requires Restart

Real Kiosk is a Firefox extension that defaults to full screen, disables all menus, toolbars, key commands and right button menus. Alt+Home still takes you home. ...

Rated 4 out of 5 stars (106)
98,776 users

Download Manager (S3) Requires Restart

View and manage downloads from a tidy statusbar

This is a new life in Firefox 26+ for old well-known addon Download Statusbar

New Features: Replace Downloads Library page.
Now you have full control of your downloads history!

Rated 5 out of 5 stars (300)
98,519 users

Selenium IDE Requires Restart

Selenium IDE is an integrated development environment for Selenium tests. It is implemented as a Firefox extension, and allows you to record, edit, and debug tests.

Rated 4 out of 5 stars (14)
98,317 users

Gmail™ Notifier (restartless) Featured

Multiple account (or label) Gmail notifier (without storing passwords)

Rated 4 out of 5 stars (265)
95,075 users

UnMHT

UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.

Rated 4 out of 5 stars (229)
93,171 users

X-notifier (for Gmail,Hotmail,Yahoo,AOL ...) Featured

Notifier for gmail, yahoo, hotmail, aol and more webmails.
X-notifier(aka WebMail Notifier) checks your webmail accounts and notifies the number of unread emails...
Supports : gmail, yahoo, hotmail, POP3/IMAP, facebook, twitter and more

Rated 4 out of 5 stars (1,699)
92,910 users

User Agent Overrider

Override browser user agent string

Rated 5 out of 5 stars (57)
92,816 users

Saved Password Editor Requires Restart Featured

Adds the ability to create and edit entries in the password manager.

Rated 5 out of 5 stars (231)
91,540 users

WhatsApp™ Desktop

WhatsApp™ Desktop provides an easy access to WhatsApp Web, and notifies you of incoming posts.

Rated 4 out of 5 stars (60)
90,787 users

Privacy Badger

Protects your privacy by blocking spying ads and invisible trackers. Warning: This add-on is in alpha, so you may find some bugs! Read more: https://www.eff.org/privacybadger

Rated 4 out of 5 stars (112)
90,322 users

FirePath Requires Restart

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 (22)
89,388 users

Google Scholar Button

Lookup scholarly articles as you browse the web.

Rated 4 out of 5 stars (11)
89,123 users

HttpRequester Requires Restart

A tool for easily making HTTP requests (GET/PUT/POST/DELETE), viewing the responses, and keeping a history of transactions.

Rated 5 out of 5 stars (55)
88,977 users

Video WithOut Flash

Watch videos without flash

Rated 3 out of 5 stars (62)
87,698 users