I searched for cost and fee and did not find my answer. MapHub says “Try for free” but for how long and how much does it cost after?
There will be a premium package after the beta period, but most of the functionality will continue to be available for free. Public maps using MapHub basemaps will always be free.
Does anyone know, if there is an open active development somewhere? (github, etc) so someone can contribute and other stuff?
Please let me know!
The MapHub web app is not open source. What is open is the underlying OpenStreetMap data, used by various basemap providers, including the MapHub basemaps.
You can contribute to OpenStreetMap and improve the map for all users across the world. You can read about contributing to OSM at https://learnosm.org/