How do I retrieve metadata in draft and registered state with the REST API?

To see the draft and registered state metadata in the response, you need to authenticate, otherwise you will only see the public facing DOIs (in findable state)

For example, you can retrieve all the DOIs from the command line with cURL as follows:

curl -X GET -H "Content-Type: application/vnd.api+json" --user YOUR_REPOSITORY_ID:YOUR_PASSWORD https://api.test.datacite.org/dois​