Google have for almost every service an API, but I can't find any API for the Google Developer Console access so I can check the usage of my credentials.
Doe someone know if this API is available and how it works (if it's available)?
There is only one API that gives you access to data in Google Developers console its called Google Cloud Resource Manager API . Unfortunately for us it is extremely limited in what it can do.
Last I checked it does not give you access to check your credentials or quota usage. sadly
My blog post about it when it was released: Google Developer console API