German Digital Library releases API by Lieke Ploeger.
From the post:
Last month the German Digital Library (Deutsche Digitale Bibliothek – DDB) made a promising step forward toward further opening up their data by releasing its API (Application Programming Interface) to the public. This API provides access to all the metadata of the DDB released under a CC0 license, which is the predominant share. The release of this API opens up a wide range of possibilities for users to build applications, create combinations with other data or include the German digitised cultural heritage on other platforms. In the future, the DDB also plans to organize a programming competition for API applications as well as a series of workshops for developers.
The official press release.
Technical documentation on the API (German).
A good excuse for you to brush up on your German. Besides, not all of it is in German.