Cataas vs RandomDog

Cataas ("Cat as a Service") is a free, open-source REST API that returns random cat images and animated GIFs, filterable by tag, with options to overlay custom text or crop a specific position. A JSON mode (?json=true) returns the image's metadata — id, tags, and direct URL — instead of the binary file itself. It's maintained on GitHub under the cataas org with no signup or pricing tier; a Donate link is the site's only monetization.

RandomDog's woof.json endpoint returns a JSON object with a file size and a direct URL to a random dog photo, GIF, or video clip from a donation-funded, community-submitted collection. A filter or include query parameter can exclude or restrict results to specific file extensions, such as skipping mp4 clips.