The top 25 most used Firefox add-on in Alerts & Updates category

The best security you can get in a web browser! Allow potentially malicious web content to run only from sites you trust. Protect yourself against XSS other web security exploits.

Displays a country flag depicting the location of the current website's server and provides a multitude of tools such as site safety checks, whois, translation, similar sites, validation, URL shortening, and more...

Tomato Clock is a simple browser extension that helps with online time management.

The best way to see the weather right in your browser. Easier than looking outside!

Get auto-updated RSS feed bookmark folders.

→ Price History charts → Price Drop & Availability Alerts → Over 1 billion tracked products → Supports Amazon .com | .co.uk | .de | .co.jp | .fr | .ca | .it | .es | .in | .mx

This extension provides integration with GNOME Shell and the corresponding extensions repository https://extensions.gnome.org

Add price history charts and price watch features to Firefox when viewing product pages on Amazon. Use it to make informed purchasing decisions and to receive price drop alerts via email, Twitter, or RSS feed.

Automatically refresh tabs based on custom time intervals

Refresh web pages automatically. Auto-refresh and page monitor with specified time intervals.

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

PhishWall

Mail notifier for multiple email accounts

Get desktop notifications, read, listen or delete emails without opening Gmail or Inbox by Gmail & easily manage multiple accounts.

Secure your Mozilla Firefox browser against real-time online threats, trackers, and scams. We’ll check every site you visit, from Facebook to your bank, so nothing puts you or your data at risk. Join a growing community of 400 million Avast users.

Mail notifier for multiple email accounts

Censor Tracker is an extension that allows you to bypass Internet censorship, warns you about sites that transmit your data with government agencies, and detect new acts of censorship.

Monitor website changes and get SMS, email or push notifications on change.

Eliminate the back-and-forth of scheduling. Manage your meetings, scheduling links, and contacts — all in one place, from wherever you’re already working online.

Previously known as Google™ Shortcuts.Display all Google services as buttons or as a space-saving dropdown menu next to your address bar. Reach services like Gmail, Google Drive, Maps, Calendar, and many more in a single click from your browser.

Never miss a donation for your charity or good cause again with the easyfundraising Donation Reminder.

Shows country flag based on the server location of the active tab's url

Check4Change (aka C4C) is a simple extension that allows you to select a part of a web-page, and get notified when it changes.

Stylish timer combined with stopwatch and alarm for your browser.

Go to the pinned GMail tab. If it doesn't exist, it's created. It also alerts you the unread emails.