BlaBlaCar
Search car sharing trips
Stations and predicted arrivals for MBTA.
Boston MBTA Transit API is a free Transportation API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Official website of the MBTA -- schedules, maps, and fare information for Greater Boston's public transportation system, including subway, commuter rail, bus routes, and boat lines.
Details from mbta.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.
Search car sharing trips
Sailing times and capacities for BC Ferries
The Boston MBTA Transit API is provided by MBTA (mbta.com). Official website of the MBTA -- schedules, maps, and fare information for Greater Boston's public transportation system, including subway, commuter rail, bus routes, and boat lines.
Yes. The Boston MBTA Transit 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.
Yes. The Boston MBTA Transit API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Boston MBTA Transit API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Boston MBTA Transit API is served over HTTPS, so it's safe to use in production.