What type of authentication does the REST API use?

To create and update DOIs and metadata with DataCite’s REST API, you need a Repository account ID (like this VXCS.IBNSOS) and password. The API uses basic authentication, and the same credentials you use to access Fabrica (DataCite's web interface) can be used to authenticate your REST API calls.

More resources:

API reference documentation

API Integrations

Accounts in DataCite