Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
PDF.js brings Portable Document Format (PDF) reading capabilities to your browser using web standard technologies.
Please report issues to: https://github.com/mozilla/pdf.js/issues
This 15KB restartless add-on will add a "File" -> "Restart" menu item and a ctrl/cmd + alt + r hotkey to restart Firefox or Seamonkey.
Pretty-prints JSON content in the browser for easy, unobtrusive viewing.
This extension prevents websites from interfering with your copy and paste actions.
Note: The same functionality is now built into Firefox, you can just change the dom.event.clipboardevents.enabled preference manually.
An indicator showing HTTP/2 and SPDY support in the address bar.
Right-click on a link to instantly open it in Private Browsing mode. (Or right-click anywhere to quickly open private browsing mode.)
Adds a small badge to your tabs to alert you to (for example) new messages on Facebook. The badge is also visible when the tabs are pinned so you can see when there's something new available.