Used this a lot on Chrome was glad to see there is also a Firefox version. No longer do I need to comment on someones post saying "Source" knowing that its not their art to begin with xD

Useful! But Google's API seems changed, so hope the author will update this addon.

doesn't work, opens an empty window

Works flawlessly, except when you open a second window, in that case, if the search opens in a new tab, it doesn't matter if the setting is "next to current", the new tabs always opens rightmost of everything.
This only affects a new window, searches in the first main window behave correctly

81 évesen nem értem mire jó ez ?

Abandoned by developer, there are now better OSS tools available

Super merci

Google image search is busted.
Edit: I figured it out, but I'm going to keep the low rating because this version of the extension has been left to rot while the Chrome version gets regular updates.

Here's the solution ー
Search URL: https://lens.google.com/uploadbyurl
Search Variables (One per Line): url=::$URL::

one of the best!