Postman is a popular API development platform. Their client app enables developers to create, save, and execute requests and inspect responses.
Look for the Run in Postman link on each Management API's landing page.
Alternatively, open the Bloomreach public Postman workspace, select the relevant API, and use the Create a fork option.
The Postman collections include a BR Content environment.
The only thing needed to use the Postman collection is to set up the environment variables:
brxHost: the URL of your Bloomreach Content environment
x-auth-token: the Authentication token