Crowd 2.0 and later
You can use a REST plugin module type to create plugin points easily in Crowd by exposing services and data entities as REST APIs.
REST APIs provide access to resources via URI paths. To use a REST API, your plugin or script will make an HTTP request and parse the response. You can choose JSON or XML for the response format. Your methods will be the standard HTTP methods like GET, PUT, POST and DELETE.
Because the REST API is based on open standards, you can use any web development language to access the API.
We used the REST plugin module type to develop Crowd's REST APIs for Crowd 2.0.
The REST plugin module type is bundled with Crowd 2.0 and later.
To learn how to add your own REST APIs to Crowd and other Atlassian applications, please take a look at the documentation for the REST plugin module type.