It works except for the Google Search. It instead takes you to the search engine for Google Images, not the reverse search.

Mostly works except for the Google option.

Works fine except for the Google option, it doesn't work

Just a reminder, theres a fix for Google on the previous page

google image search just redirects me to google image search homeage even though for a moment i can see the url is tryingto search the image's url

Google image search doesn't work for a long time now.

Google Search option does not work as of right now

The icons for the search engines are outdated, and lacks the additional functionality that http://addons.mozilla.org/firefox/addon/search_by_image provides.

Have used this extension for a very long time. Works like a charm

Edit: Moved to "Search by Image" add-on by Armin Sebastian. This one still works, but alternative is actively developed, supports more engines out of the box, detects images behind elements that this add-on cannot detect and more.

Can't test this extension. Does nothing on Firefox on Android

It requests too much permissions (https://addons.mozilla.org/cs/firefox/addon/fast-image-research/ requests less). Can NOT find link to open source platform like a Github.