Velib Open Data API.
Velib metropolis, Paris, France API is a free Transportation API that requires no API key, is served over HTTPS and does not support CORS, so it should be called from a server.

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Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Community maintained, developer-friendly public transport API
Yes. The Velib metropolis, Paris, France API is listed in the Transportation 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 Velib metropolis, Paris, France API requires no authentication, so you can start making requests without signing up.
Not directly. The Velib metropolis, Paris, France API does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The Velib metropolis, Paris, France API is served over HTTPS, so it's safe to use in production.