HSL Developer Community is open for all individuals and organisations interested in the Open Data and Open Source software regarding Helsinki Region Transport HSL or wider. HSL is the public authority that plans and procures the public transport (ferry, tram, metro, train, bus) within its member municipalities (Helsinki, Vantaa, Espoo, Kauniainen, Kirkkonummi, Kerava, Sipoo, Siuntio and Tuusula).
HSL's next-generation journey planner, in cooperation with Finnish Transport Agency's national Journey.fi.
Digitransit project includes digitransit-ui user interface and back-end services providing APIs for public transportation data, geocoding and maps.
Most vehicles in the HSL area publish their status to a MQTT server. MQTT clients can subscribe to these status messages and filter them based on e.g. transport mode and geographical area.
HSL OpenMaaS API can be used to order public transport tickets, which can be embedded into your own mobile application.