This API can be used to check if a german license plate is available, or is actively in use.

Operations are:

function=offices
&plateTokens=AA

Means: find all offices with the “AA” prefix (first part of the license Plate), use this to get the office ID

and

function=availability
&officeId=5b1ba1a143d2ec142d9dd685
&city=GD
&letters=FF
&numbers=991

(optional vehicle=motorcycle)

means check the availability of GD-FF-991 in officeId for GD.