FOSDEM 2025 - MapTCHA, the open source CAPTCHA that improves OpenStreetMap

MapTCHA is an open-source CAPTCHA solution that combines bot prevention with OpenStreetMap improvement by having users verify AI-predicted building outlines in aerial imagery. The system leverages human verification to validate both known and unknown cases, aggregating responses through voting to suggest new locations for OSM mapping while using fAIr, an open-source AI mapping system by HOT.