Neither the open (geo)data initiative and, needless to say, the open source for geospatial one, are the new kids on the block anymore. Crucial steps have been taken all over the world in establishing the framework of openness, collaborative development and transparency ranging from hands-on events - such as code sprints or collaborative data gathering - mapathons - to funding opportunities and legislative measures. In this context, we present a 3 years-old EU supported initiative founded on open source and open data and that has reached maturity. In our talk, we present the potential support that such initiatives have in the wider framework of environmental monitoring and reporting across Europe - Geo-harmonizer. Geo-harmonizer stands for EU-wide automated mapping system for harmonization of Open Data based on FOSS4G and Machine Learning. The project unfolded between 2019 and 2022 and was co-financed under Grant Agreement Connecting Europe Facility (CEF) Telecom project 2018-EU-IA-0095 by the European Union.