Caption Bot is described as 'I can understand the content of any photograph and I'll try to describe it as well as any human. I'll analyze your photo, but I won't store or share it' and is an website in the Photos & Graphics category. There are three alternatives to Caption Bot, not only websites but also apps for Android. The best alternative is Crowdsource, which is free. Other great sites and apps similar to Caption Bot are ARTigo (Free) and MetaData Games (Free).
ARTigo is an online game with the aim to supply artworks with tags. The same artwork is simultaneously shown to you and a co-player. The game now consists in describing the artwork accurately with tags.
Metadata Games is a digital gaming platform for gathering data on photo, audio, and moving image artifacts. The platform entices players to visit archives and explore humanities content while contributing to vital records.