Geoserver
Hosts various geospatial datasets: implements WMS and WFS
Infopankki
Infopankki API provides interface to content of infopankki.fi website
Kore
Kore API contains the complete Helsinki school history database operated by the City Archives. It is used by https://koulurekisteri.hel.fi.
Linked Events
Aggregates data about events around the city
Open311
An API for reporting issues and giving feedback
OpenAhjo
Decision data like meetings, agendas, and decisions
Respa
An API for making resource reservations, such as booking a practice room or a meeting space
Service Map Backend API
Provides service point data with advanced filtering for interactive service point applications
Snowplows
The snowplow API allows querying the real-time and historical locations of snowplows in the Helsinki area.
Statistics
Query the city's statistical databases