AdoptAPet vs MeowFacts

AdoptAPet's free Pet List API lets a registered shelter or rescue pull its own current adoptable-pet listings — name, photo, breed, and a link back to the pet's page — for display on its own website; it doesn't cover other shelters' animals or expose network-wide search. Access needs a per-shelter API key passed as a key query parameter to endpoints like api.adoptapet.com/search/pets_at_shelter, confirmed live by a real GET that returns a JSON invalid_key error rather than a redirect or outage, with a separate OPTIONS preflight and that same GET both echoing access-control-allow-origin: * back for a test Origin header. The official documentation page now sits behind a shelter-account login (a live probe returns 401 with a Basic-auth challenge, a change from when it was openly readable), but the API endpoint itself remains fully live and free, returning JSON or XML depending on the output parameter.

meowfacts is a free, keyless REST API that returns one or more random cat facts as JSON, with count and id query parameters for multiple or specific facts. A lang parameter serves community-translated fact sets in around 15 languages (English, Spanish, French, German, Korean, Russian, and others, by browser-style ISO 639 code). It's an open-source (GPL) side project hosted on a free Heroku dyno and documented via SwaggerHub, with no signup, key, or pricing tier.