Developer
How can I access the API?
Learn how to access the API as a developer and use your account data in your own applications.
Updated on August 22, 2026
The interactive Billnado API documentation is available at api.billnado.be/documentation. This URL is publicly accessible and may be freely used and shared. It allows you to explore the available endpoints, request models and responses. Authentication is required to make secured API requests.
API definitions
The API documentation is divided into multiple definitions that correspond to different groups within the software. Examples include client, account, support and accountant. Each definition contains the endpoints associated with that group.
You can select the desired definition in the documentation. The available endpoints and access to them may differ between definitions and depend on your permissions.
Authentication
The API documentation provides two authentication methods:
- OAuth 2.0
- A Personal Access Token (PAT)
OAuth 2.0
OAuth 2.0 is currently the supported authentication method. Use it to securely grant your application access to the API on behalf of a Billnado account.
Personal Access Token
Support for Personal Access Tokens is planned but not yet available. You cannot currently request or use a PAT. This option will be added in a future release.
Until then, use OAuth 2.0 to access the Billnado API.
