General Data Transit Feed (GTFS) is the standard set for all transit operators & developers.
Do you like API keys and mucking around with request headers?
How about rate limits and CORS restrictions?
We at Smart Cities Transport have setup a service for the GTFS-realtime feeds to allow unlimited, keyless, unrestricted access. You can test it here & send us feedback such as improvement requests, issues, and questions
Please note that you still have to adhere to license
You can guess the other available URLs by exploring the GTFS-realtime APIs and inserting:
share.smartcitiestransport.com/ in the right spot: