FactGrid is a free, multilingual, shared database for historians, a joint initiative of German research centers. The platform runs on the versatile Wikibase (like Wikidata). The data can be used freely by anyone but can be edited only by historians. At the moment there are 150,000 items in the data set and it is constantly expanding with new projects. The full database of the German National Library will be integrated into the platform.

They welcome new research projects but it is also possible to upload older datasets or migrate finished projects to the website. To browse and request an account: https://database.factgrid.de For more detailed information on the platform: https://blog.factgrid.de/archives/1591