CitySDK is a project that's designed to make it easier for cities to expose useful information to developers. So far, the cities of Lisbon, Helsinki, Lamia, Rome, and Amsterdam have joined the project.
The CitySDK Mobility API exposes information on basic geography, street-level mapping, public transportation, and Amsterdam-specific infrastructure and transportation. Its major data sources include OpenStreetMap, openOV, and DIVV. The CitySDK Mobility API can be used, for example, to discover museums located in Utrecht, get the locations of stops along a given tram line, or retrieve a list of towns located in the Netherlands.