Mozilla Add-ons - Download Firefox extensions and themes. They’re like apps for your browser. They can block annoying ads, protect passwords, change browser appearance, and more.
extensions.af - A site to find the dopest Chrome extensions out there
Addoncrop - Extends the functionality of your web browser
Plugins Addons Extensions - Plugins Addons Extensions is a platform that provides a one-stop-shop for all the latest Chrome extensions that can help you to run your business.
Chrome Extension Downloader - Chrome Extension Downloader is the name of a website dedicated for downloading and Chrome extensions.
Opera Add-ons - Get extensions and themes for the http://alternativeto.net/software/opera browser.