Create/customize beautiful digital maps.
Mapbox API is a free Geocoding API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Details from docs.mapbox.com.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
The Mapbox API is provided by Mapbox (docs.mapbox.com).
Yes. The Mapbox API is listed in the Geocoding 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.
Yes. The Mapbox API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Mapbox API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Mapbox API is served over HTTPS, so it's safe to use in production.