IQDB is described as 'Multi-service image searchUpload an image or thumbnail from a file or URL to find it (or similar images) among:Haruhi doujins (Haruhi doujins)Danbooru (anime'. There are more than 10 alternatives to IQDB, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Google Chrome. The best alternative is TinEye. It's not free, so if you're looking for a free alternative, you could try NooBox or SauceNAO. Other great sites and apps similar to IQDB are Search by Image (Free, Open Source), trace.moe (Free, Open Source), Safe Design (Paid) and RevIMG (Paid).