In addition to an extensive REST API, the connect+ portal also offers a PUSH API with Data Streams.
With the REST API, a lot of information can be obtained from the portal, and a number of controls and automations can be realised. You can get a comprehensive overview of available requests and sample responses directly in the API documentation.
Via data streams, it is also possible to trigger API requests based on an event (PUSH API). An example of how you can generate a mail when an event occurs can be found in this help article.