Use the sandbox environment to play around in. Requests made in the sandbox never hit the banking networks, and inccur no costs. Only endpoints that do not require authentication can be use in this manner, for authorization please use the demo endpoints: https://api-demo.novemberfirst.com/swagger/ui/index
You can use our demo web portal, as well as the demo API with valid access tokens and a valid Partner ID. The end-points can be seen below under N1.Api.