Gemeentelijk Gegevensmodel (GGM)

Challenge

Dutch municipalities operate with hundreds of applications, disparate sources, and a proliferation of terms that look alike but mean different things. Despite years of digitisation, no overarching picture existed of “what a municipality deals with” in data terms. That made data warehouses fragile, APIs single-use, and standardisation an endless committee exercise. In 2019, the municipality of Delft commissioned me to build not just another domain model, but the integral data model nobody had dared to attempt.

What we built

The GGM is a logical information model that describes the entire municipal domain across thirteen policy areas: from Public Order & Safety to Education, Social Services, Transport and Economic Affairs. It also contains a Core layer with concepts that recur everywhere: Person, Case, Location. The model is built in UML (Enterprise Architect) and automatically generated into HTML documentation, database schemas, and linked-data representations. It deliberately reuses existing standards (RSGB, RGBZ, iWmo, IMBOR) rather than replacing them, linking those standards to the domains through explicit mappings.

Key design decisions

• Integral, not federated. One coherent model instead of a collection of domain models. This enables cross-domain analysis (a client who appears in both social services and debt assistance) and forces decisions where overlap arises.
• Built from Delft’s practice, not from a national working group. The model was tested from day one against real applications, real questions, and real reports. That made it operational before it became a standard.
• Open source and actively maintained. Not a frozen reference document, but a repository with releases, an issue tracker, and a growing community of municipalities proposing changes.

Results and adoption

The GGM is now used by more than 150 municipalities as the foundation for data warehouses, API specifications, reporting pipelines, and standardisation initiatives. The Common Ground Expert Review Group awarded the model a Gold qualification: the highest in the portfolio. The accompanying GGM-Mappings repository collects public mappings to vendor systems, so implementations reinforce each other instead of duplicating work. The model has become exactly what it was meant to be: a shared language that municipalities adopt voluntarily.

Recognition and third-party adoption

The GGM is not only used by municipalities; it is also actively embraced by vendors, knowledge institutions, and trade media:

Awards and qualifications

• GemeenteDelers 2022: the GGM won the GemeenteDelers award at the VNG congress in the information technology category.
• Common Ground Gold: the Expert Review Group awarded the GGM the highest qualification in the Common Ground portfolio.

Vendor adoption

• PinkRoccade offers municipalities full-service delivery up to the GGM and integrates the model into iCollect.
• Centric delivers data GGM-compatible to municipalities and published ‘Data as a Service by Centric’ on the Kennisnetwerk. At Centric Relatiedag 2025 (11 September, 300+ attendees), Arjen Brienen and Ashkan Ashkpour gave a session on the GGM to a full audience.
• Enable U positions the GGM as the key to data-driven municipal policy and connects their Scamander platform to the model.
• Avineon-Tensing describes the GGM as a foundation for nationwide collaboration.
• Other early adopters: Aurai, Beeminds, Centennium, Insumma, Scamander, and Microsoft.

Trade media and knowledge institutions

• Computable (Oct 2024): extensive article on the rise of the GGM, with a community of 400+ members.
• iBestuur (Feb 2025): report on the GGM meetup with 100+ participants, including TU Delft professor Marijn Janssen.
• iBestuur (Nov 2022): article on the GemeenteDelers award and the open source approach.
• VDP / Publieksdiensten (Jun 2022): case description of the GGM as a shared data foundation.
• VNG: practice example on the VNG website.
• Kennisnetwerk Data en Samenleving: the GGM community with 400+ members on the Pleio platform.

International

• The municipality of Trondheim (Norway) has adopted the model; there is interest from other European cities and research institutions.