Open data

Open data is information that anyone is free to access, use and share, for any purpose — published in machine-readable formats under a licence that removes the usual restrictions. For governments it means putting the data they already hold, from budgets to bus timetables to sensor readings, online for the public rather than locking it inside internal systems.

The bet is that value appears when others can build on the data: researchers, journalists, startups and residents can spot patterns, make apps or hold the city to account. Small towns increasingly run open urban-data platforms fed by their own sensors — Bad Nauheim publishes footfall, traffic and smart-bin data through a public 'citizen cockpit', Alsfeld is building an open platform for parking, air quality and heat, and

Open by default has real limits. Publishing a raw spreadsheet nobody maintains helps no one; useful open data needs documentation, stable formats and upkeep. And 'open' must stop where privacy begins — movement or sensor data can re-identify individuals if released carelessly, so cities aggregate and anonymise before opening the doors.