It is easy to use: Just type in your german VAT ID in the first field and the VAT ID of the EU company in the other field.
IMPORTANT: You cannot check german VAT ID because this is not allowed in germany without special procedures to get the "ok" for that.
The Database of the german tax court will be refreshed by the german tax court. No guarantee or warranty for correctness of the data.
I hope it it usefull for you.