Tenants with version 1.43+ have access to an API to read and write access and user data and to read data through KEX-scripts. On https://your_tenant.konstrukt.net/api/documentation/ there is documentation and testing tools for the available API endpoints.
Reading data through KEX scripts
The endpoint /api/v1/kex offers the ability to read data via an API endpoint in a flexible way. Using this endpoint, you can send a KEX script and retrieve data in json-format.
Documentation on KEX and how to use it is available in the article What is KEX? or directly at https://your_tenant.konstrukt.net/api/documentation/kex