Add-ons

DownThemAll! by Nils Maier, Federico Parodi, others

The first and only download manager/accelerator built inside Firefox!

User Agent Switcher by chrispederick

The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.

Password Exporter by Justin Scott (fligtar), Jorge Villalobos

This add-on allows you to export your saved passwords and disabled login hosts using XML or CSV files that can be imported later.

Note: This add-on won't work in Firefox 57. It may eventually if the APIs to access passwords are implemented.

Element Hiding Helper for Adblock Plus by Felix Dahlke

Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.

UnMHT by arai_a

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.

Speed Dial by Josep del Rio

Direct access to your most visited websites

ReminderFox by Tom Mutdosch, Daniel Lee, others

ReminderFox displays and manages lists of reminders and tasks. ReminderFox uses easy-to-use lists with warnings/alarms to remind you of all your important appointments.
Synchronize ReminderFox with other calendars as well.

Notepad (QuickFox) by InBasic, J Benthum

Everyday note-taking solution.

QuickPasswords by Realraven (Axel Grude)

Retrieve your Passwords the quick way! Never retype or display your secure passwords on screen anymore - put the password where you need it - the login form or the clipboard.

Now also includes SSO change (multi-domain pw) and Backup + Restore.

Open Multiple Locations by Jordan Matuszek

Adds a "File" menu option to open multiple locations at a time.

Restartless Restart by Erik Vold

This 15KB restartless add-on will add a "File" -> "Restart" menu item and a ctrl/cmd + alt + r hotkey to restart Firefox or Seamonkey.

ImageTweak: zoom/rotate images and videos! by Carlo Alberto Ferraris

A no-clutter image viewer for Firefox that allows you to zoom, rotate and display images/videos against a custom background. ImageTweak is a must-have addon for any photographer or photography-loving user.

autumn the new spring by Osos Star

Three winter cuties by Rallara