The CitySDK Mobility API is a layer-based data distribution and service kit, which makes European mobility data and services interoperable. The API is part of CitySDK, a project funded by the European Union in which eight cities and more than 20 organisations collaborate. The CitySDK Mobility API makes it possible for developers and data owners to access and modify mobility data (e.g. public transport schedules, real-time traffic data, planned roadwork and parking space availability) through a uniform interface, in Amsterdam, Manchester, Helsinki and Rome alike. The API links different datasets from different data sources to addressable objects in a city, such as train stations, bus stops, roads and neighbourhoods. Many of those objects exist in the OpenStreetMap database; the CitySDK Mobility API uses OSM as a geospatial base layer to which it links data from other datasets. For example: GTFS schedules, Open311 service requests and real-time weather information can all be linked to a OSM node with the ""highway=bus_stop"" tag, making it very easy for data owners, city officials and developers to find and access data about the same object across different data sets. Developer's portal: http://dev.citysdk.waag.org/ API endpoint: http://api.citysdk.waag.org/