Open Source and Open Data: the building blocks for a Geo-harmonized understanding of our environment In this talk, we will present a 2fold 3years initiative that builds on open source and open data. It is a story of harmonization and accessibility, all supported by free and open source for geospatial - foss4g. It is the story of the Geo-harmonizer. Geo-harmonizer stands for EU-wide automated mapping system for harmonization of Open Data based on FOSS4G and Machine Learning and it is unfolding in 2 ways. On one hand, significant efforts have been invested into obtaining new added value time series map products based on open sources for remote sensing data, such as Landsat, Sentinel, MODIS etc. , machine learning frameworks on cloud infrastructure and using High Performance Computing. On the other hand, efforts have been dedicated to the development of web-base, scalable and modular system fit to provide hosting and accessibility to various time series thematic geospatial map products. This system translates into an intuitive and very responsive data portal using open source software, such as Geoserver and GeoNetwork. This is a European story, yet our approach is replicable everywhere in the world, towards a complete, harmonised and cross-boundaries understating of our environment through open data and open source - a Geo-harmonised approach. https://maps.opendatascience.eu/ https://gitlab.com/geoharmonizer_inea/eumap This talk gives an overview on all activities developed during the first 2 years of the Geo-harmonizer initiative, with an emphasis on the foss4g usage and development, as well as the open data used to obtain harmonised cross-boundaries geospatial datasets. Track – Use cases & applications Topic – Data collection, data sharing, data science, open data, big data, data exploitation platforms Level – 2 - Basic. General basic knowledge is required.