Navitia.io is an API that helps people access and use public transportation data. It provides services for performing journey computations, getting line schedules, finding next departures, and discovering isochrones. Isochrones are locations that can be reached in the same amount of time from a person's starting point. This part of the API could, for example, be used to discover which stations could be reached within the next 60 minutes.
The street network used by navitia.io is extracted from OpenStreetMap, and all of the public transport data comes from networks that provide their timetables as open data.