Testing a REST API while or before writing the code that uses it is essential to ensure that it works correctly.
Check out the API documentation, build the Request and from Postman, Advanced Rest Client or simply, from any script, point to TestTools (APITEST V1.0) returns a JSON (Key Content) with all the parameters sent and as they will be received by the Api Server. Version 2.0 will include HTTPS.
Enjoy :-)