City Bikes around the world.
City Bikes API is a free Sports & Fitness API that requires no API key, is served over HTTPS and has unconfirmed CORS support.
Details from api.citybik.es.

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The City Bikes API is provided by CityBikes API (api.citybik.es).
Yes. The City Bikes API is listed in the Sports & Fitness category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
No. The City Bikes API requires no authentication, so you can start making requests without signing up.
CORS support for the City Bikes API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The City Bikes API is served over HTTPS, so it's safe to use in production.