The most popular Lunapic.com art filters are now available via API. A full list of over 100 supported art effects are listed here http://lunapic.com/?filters
Ribbet is an online photo editor with free cloud storage, complete editing history, thousands of effects, filters, hand-picked shapes, designer fonts and borders. Ribbet also has bookmarking to allow favorite effects to be stored. With the Ribbet API, developers can integrate the full functionality of Ribbet into their application or website.
Unstellar api will transfer your photo to art! Providing multiple art effects and styles, you can turn photo into artwork with Unstellar. Unstellar is the app api like Prisma, GoArt, Painnt and other style transfer apps. Example app https://play.google.com/store/apps/details?id=com.geron.unstellar