window.crypto.signText replacement plus enhancements
Poster Requires Restart
A developer tool for interacting with web services and other web resources that lets you make HTTP requests, set the entity body, and content type. This allows you to interact with web services and inspect the results...
Accelerate your SEO efforts on the fly. SEOquake is a free plugin for browsers that provides you with key SEO metrics for a specific page, along with other useful tools such as SEO Audit and many others.
A Statusbar with speed, percentage, time and loaded size (similar to Opera's one)
URL Fixer Plus RU and UA Requires Restart
Extended URL Fixer for RU and UA
An indicator showing HTTP/2 and SPDY support in the address bar.
Html Validator Requires Restart
HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon
For Online HTML 5 validation, you need 0.962
Proxy Switcher Featured
Access to the complete Firefox's proxy settings right from a toolbar panel
FireMobileSimulator Requires Restart
this add-on simulates japanese mobile device.
this add-on support DoCoMo, Au(KDDI) and SoftBank device.
Scriptish Requires Restart
The greatest user script engine on the Internet (a fork of Greasemonkey).
XHTML Mobile Profile Requires Restart
Firefox does not natively support the mime-type application/vnd.wap.xhtml+xml. This is one of the possible mime-types for XHTML Mobile Profile. This addon adds support for this mime-type.
Classic Toolbar Buttons Featured
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions.
Beta builds on versions page!
Advanced Cookie Manager Requires Restart
A must have tool for Web Developers and Testers to Manage and monitor web cookies.
Export / Backup
Import / Restore
Available in English, French, Spanish, German and Italian languages.
Font Finder Requires Restart Featured
FontFinder is created for designers, developers and typographers. It allows a user to analyze the font information of any element on a page, copy any piece(s) of that information to the clipboard, and perform inline replacements to test new layouts.
This extension provides a list to almost all the settings that you may need to alter in order to enhance Firefox's speed.
ShowIP Requires Restart
Show the IP address of the current page in the status bar. It also allows querying custom information services by IP (right click) and see location and avaiable vouchers for shopping sites. Additionally you can copy the IP address to the clipboard.