Plaghunter is described as 'reverse image search that scans where your images are being used online'. There are more than 10 alternatives to Plaghunter, not only websites but also apps for a variety of platforms, including Windows, Google Chrome, Opera and Firefox. The best alternative is TinEye. It's not free, so if you're looking for a free alternative, you could try NooBox or Search by Image. Other great sites and apps similar to Plaghunter are Unicheck (Paid), IQDB (Free), Search by Image (by Google) (Free) and RevIMG (Paid).
Search by Image is a Firefox extension which enables you to initiate a reverse image search from the right-click context menu or the browser toolbar, and comes with support for more than 30 search engines.
Multi-service image search Upload an image or thumbnail from a file or URL to find it (or similar images) among: Haruhi doujins (Haruhi doujins) Danbooru (anime artwork) Konachan (anime wallpapers) Moe.imouto.
Google Reverse Search, available at reverse.photos, lets you search by images instead of keywords. Upload a picture from your desktop, tablet or mobile phone, and Google will show all the other web pages on the Internet that have similar images.
Adds an option to the context menu to search with an image on Google, Bing, Yandex, TinEye, SauceNAO, IQDB or custom search engines. You can also choose more than one and they will be shown in a submenu!.