Digital public infrastructure for cities is open-source software, free for any city or state to use, on which public services such as property tax, water connections, trade licences and complaints run. The best-known example in India is DIGIT, built by a nonprofit in Bengaluru. Open source means that the code is published, and anyone may use it, change it and share it without paying a licence fee.
Why build it this way? India has thousands of cities and towns. Each one collects property tax, gives water connections, issues birth certificates and handles complaints. Most cannot afford to build these systems themselves, and buying a separate product for each city would cost far more. With one open platform, each service is built once, and any city or state can use it. Software that anyone may use, change and share for free is called a digital public good.
The platform is built from modules that share common parts. One module handles property tax. Another handles water and sewerage connections. Another handles public grievances, the complaints a resident makes about a broken streetlight or uncollected garbage. All the modules share the same login, the same records of citizens and properties, the same payment service and the same receipts. Payments are taken through a payment gateway, so residents can pay by UPI, card or net banking. A city can also make its bills payable through a bill payment platform, so that residents can pay from any bank's app. The money collected is posted to the city's accounts, which may run on a government ERP.
Consider a town in Odisha with 70,000 residents, whose municipal council has just started using the platform for water connections. A shopkeeper applies on the town's website for a new connection. He uploads his property tax receipt and an identity document, and pays the ₹1,500 application fee by UPI. The application goes to a junior engineer, who visits the shop on day 4 and approves it. On day 6, the system calculates the connection charge of ₹6,200, and he pays it. A plumber is assigned, and on day 11 the connection is made and the first water bill is created. At every step, the shopkeeper receives a text message with the status.
Who pays for it, if it is free? The software is free, but setting it up is not. A state usually pays an IT services firm to install the platform, adapt it to local rules and run it. The nonprofit that builds it is funded by grants from foundations and by government contracts. This is one version of the open source business model.
How is it different from India's national digital public infrastructure, such as Aadhaar, UPI and DigiLocker? Those are single national systems that everyone in the country uses. This platform is software that each city or state runs as its own copy, for its own local services.