Why do I need to have log-in for sandbox and production?

We have two environments, which you'll use for different purposes. You'll use the sandbox developer portal, when you're testing. You'll use the production developer portal, when you've completed testing in sandbox, and are ready to handle real payments in production. During your testing phase, use the Sandbox endpoints and your test account details in each MobilePay API request you make. 

The sandbox URL is 

https://api.sandbox.mobilepay.dk

The production URL is

https://api.mobilepay.dk