Extensions switcher - Menu for quick extensions control
TinEye - Reverse Image Search to help find an image's source, duplicates or altered versions.
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.
GImageReader - gImageReader is a simple Gtk/Qt front-end to the Tesseract OCR Engine.
Extensity - Quickly enable/disable Google Chrome extensions.
Yandex.Images - search for images on the internet, search by image