First off, you will need a regular Mollie account. You can create it in the usual way.
Go to our Dashboard, or switch to our new Dashboard if you are still using the old version.
Select Apps from the menu at the top:
Select Are you a developer? and activate your account.
You can create a new app right away via Register new app:
You will receive the Client ID and the Client Secret right away. These two data will allow you to create a link to the API.
Please contact us if you want to let other Mollie customers use your app as well.