OC Transpo API.
Transport for Ottawa, Canada API is a free Transportation API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.

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.
Data about positions of Metro vehicles in real time and travel their routes
Yes. The Transport for Ottawa, 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 Ottawa, Canada API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Transport for Ottawa, 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 Ottawa, Canada API is served over HTTPS, so it's safe to use in production.