Yes, it's SauceNAO but with a wider range of options and you don't have to find and paste the image's URL every time you want to do a search.

You also have a nice trick for images that can't be downloaded through conventional methods like right-clicking on the picture: select the add-on image picker to get a preview (it's the original image!) that you can download easily.
Works like a charm for sites like Pixiv.