Niceboard provides a private API to subscribers on the Business plan. You can access the API with the following steps:
1) Tap Manage board > Automation > Private API.
2) In the middle of the page, you will find your secret API key and your routes.
3) Tap on each route to review additional documentation for that route.
The following screenshot shows a list of routes. Additional documentation can be found in your dashboard by following the steps above: