Cat Facts vs Cataas

catfact.ninja is a free, keyless REST API built on Laravel that serves a curated database of cat trivia facts alongside a separate cat-breed dataset (coat, pattern, country of origin, and more). Its /fact endpoint returns one random fact, while /facts and /breeds paginate through the full ~166- and 98-page collections respectively. The API documents itself via a Swagger UI hosted at its own root and throttles unauthenticated requests to 100 per minute per IP.

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.