Hakunapi (https://github.com/nlsfi/hakunapi) is a modular and high-performance server implementation to build open and standardized geospatial feature services. It allows mapping agencies, cadastral register authorities and other organizations dealing with geospatial data to provide API-driven access to valuable registers and rich geospatial databases.

The core of Hakunapi is based on semantic and technical interoperability. It supports OGC API - Features specifications standardized by OGC (The Open Geospatial Consortium). This enables API services to be consumed both by machines (structured data via JSON content) and by humans (via navigable HMTL pages) as presented by Hakunapi-based demo service: https://beta-paikkatieto.maanmittauslaitos.fi/inspire-addresses/features/v1/

The demo service is based on the encoding rules specified by the European Union's INSPIRE Directive which aims at building a spatial data infrastructure for the purposes of EU environmental policies. Hakunapi as a solution makes it possible for national mapping agencies and other responsible organizations to provide even more efficient and interoperable INSPIRE-compliant geospatial services in the future.

The development of Hakunapi started in 2018 by participating in the WFS 3.0 hackathon organized by OGC. Since then, the National Land Survey of Finland has used the solution to build multiple feature services for cadastral and topographic data based on the OGC API Features standard. The full codebase as a Java Server solution was open sourced in 2023. It was also presented at the FOSS4G (Free and Open Source Software for Geospatial) conference in June 2023.