ITSO Ltd is a non-profit membership organisation assisting standardisation of public transport ticketing in the United Kingdom.

[1] Its objectives are to: ITSO was established as a result of discussions between various UK passenger transport authorities concerning the lack of standards for interoperable smart card ticketing.

Transport Scotland and the Welsh Government have implemented ITSO in their concessionary travel schemes.

It defines the key technical items and interfaces that are required to deliver interoperability between components of a ticketing system – smart media (smart cards), points of service and back offices – and separate ticketing systems.

The ITSO member list includes most of the major bus operators, ticket issuing system vendors and passenger transport executives.