The REST API is currently only in maintenance mode. With the launch of the new - Xentral API - we will no longer be adding new functionality to the REST API, meaning we will just fix critical bugs.
The reference to this API can still be found in our handbook . The documentation is shipped with xentral and can be accessed in any xentral instance at instancename/www/api/docs.html in the browser. However, the /www/ is often not needed. Alternatively, the API documentation, organized by version, can also be found online: https://update.xentral.biz/apidoc/docs224.html
As a rule, the version can be specified in the path name. For example, version 21.1 can be found in the path docs211.html.