The Open Transport initiative released two Open Standards for transport and mobility account interoperability in January 2020.
These innovative API specifications were created via a collaborative approach using the input of over 25 different organisations and experts (e.g. transport providers, mobility-as-service software vendors, transport authorities & government departments and industry consultants).
Described as “the Open Banking for Transport” they have since been free for any organisation in the industry to adopt and adapt.
Full details and the actual specifications are available at https://opentransport.co.uk/