We encourage anyone interested in building tools to interoperate with the Dataverse to utilize our APIs. In 4.0, we require to get a token, by simply registering for a Dataverse account, before using our APIs (We are considering making some of the APIs completely public in the future - no token required - if you use it only a few times).

Rather than using a production installation of Dataverse, API users are welcome to use http://demo.dataverse.org for testing.