Открывается https://www.google.com/imghp?sbi=1 с "Поиск по картинке. Используйте для поиска в Google изображения, а не текст. Перетащите картинку сюда". Естественно, без прямых ссылок на результаты поиска. Firefox 59.0b10 x64, Windows 10.
Only works some of the time. Often just does nothing. When it works, it takes very long. Also required the container tab option to remain on, leaving the "open in new container tab" option in the right-click menu. Don't need container tabs or this anymore.
The speed for opening a page should be improved, but good addon, does the job, find similar images, and it's faster than going to Google image search page. I read another review saying it adds itself as a start page, no, I don't have this problem.
Significantly worse than other reverse image search add-ons available for Firefox, as well the reverse image search built in to Chrome. Always takes several seconds or longer to open the search page, when it works at all.