The atlas,
explained.

GreatAPIs is a directory of the programmable web: currently1,324 APIs across 51 domains, each entry indexed by the three things you check before writing a single line of code —does it need a key, does it speak HTTPS, and will the browser let you call it.

Unlike lists that only track free services, the atlas doesn't care how an API is priced. Free tiers, paid platforms, weekend projects, government open data — if it's a great API, it belongs here.

How entries are indexed

Authentication

None means you can call it immediately.API Key means a signup first.OAuth means a full authorization flow.

HTTPS

Whether the API serves traffic over TLS. Almost all do; the exceptions are flagged.

CORS

Whether browsers may call it cross-origin. Without CORS you'll need a server-side proxy for frontend use.

How the atlas is kept

Every entry is catalogued and re-verified by hand: links checked, auth requirements confirmed, categories assigned editorially. The atlas grows continuously — new APIs are added as we find them, and dead ones are flagged and hidden. The whole atlas is also published as machine-readable feeds — /index.json,/llms.txt, and /llms-full.txt — including arecord for GreatAPIs itself.