Spoofs User-Agent strings of your browser with a new one globally, randomly or per hostname
Send the page you are currently viewing to your mobile device. QR codes are generated instantly in browser and never leave your computer. Implemented with WebExtensions API and compatible with Firefox 57+.
The Ultimate online investigation tool! See detailed information about every IP Address, Domain Name and Provider.
An easy-to-use font inspector to get CSS styles of the selected element
'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!
View source code of Firefox add-ons and Chrome extensions (crx/nex/xpi) from addons.mozilla.org, the Chrome Webstore and elsewhere.
Add-on to display GitHub code in tree format
Enables the resolving of Dot-BIT domains by Namecoin. Also .emc, .coin, .lib and .bazar domains by EmerCoin. Redirecting of NXT aliases.
Cookie-Editor lets you efficiently create, edit and delete a cookie for the current tab. Perfect for developing, quickly testing or even manually managing your cookies for your privacy. Also supports Firefox for Android.
RusVPN - Free VPN Service