The Key is a contactless ITSO-compatible smartcard developed by the Go-Ahead Group used on buses, trains and other forms of public transport across various areas of the United Kingdom.

The Key uses near-field communication to electronically store and transmit information about rail and bus tickets for use on several operators across the UK.

The Key is available to customers on the majority of the deregulated bus services operated by the Go-Ahead Group in towns and cities across England.

These were standalone, self-operated machines that could issue standard adult Key smartcards by providing your personal details.

The first-line customer support teams are also unable to arrange a replacement and need to refer on the request internally.

[8][9] It is also valid for pay-as-you-go and PlusBus travel on some MetroBus and Brighton & Hove buses, as well as on GTR services between many stations on their network.

[11][12] keyGo can also be used on Great Western Railway services between Redhill and Dorking Deepdene, including break of journey.

[20] From 24 January 2018, customers can amend incomplete journeys themselves from their online account to fill in missed touches to prevent a penalty fare being charged.

[18] The keyGo system will attempt to auto-fill missing touches based on the customer's journey history with the Key and any valid tickets held on the smartcard at the time.

On 2 September 2020, GTR announced that select railcards may be added to an online keyGo account to provide discounts on rail and PlusBus transport.

[25] The ITSO standard provides a system for transit via credit balances named stored travel rights,[26] but keyGo does not use this facility for its ticketing.

This period pass is then read by ITSO-compatible smartcard readers within the keyGo area, and interpreted as valid authority to travel.

Due to the nature of keyGo's tap-on tap-off system, there are some differences between its usage and standard railway tickets.

TfL estimated that providing ITSO capability across all of their services would require the procurement of 20,000 new smart ticket readers within their controlled station facilities and buses.