
TransLink.
Transport for Vancouver, Canada API is a free Transportation API that requires OAuth authentication, is served over HTTPS and has unconfirmed CORS support.
TransLink provides access to data associated with the regional bus network, bus service operations, and major road network allowing developers to build applications enriched with TransLink data.
Details from developer.translink.ca.

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.
Washington Metro transport API
Community maintained, developer-friendly public transport API
The Transport for Vancouver, Canada API is provided by TransLink (developer.translink.ca). TransLink provides access to data associated with the regional bus network, bus service operations, and major road network allowing developers to build applications enriched with TransLink data.
Yes. The Transport for Vancouver, Canada 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 Transport for Vancouver, Canada API uses OAuth authentication, so you need to register for credentials before making requests.
CORS support for the Transport for Vancouver, Canada API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Transport for Vancouver, Canada API is served over HTTPS, so it's safe to use in production.