Introduction to the Billit API

Welcome to the Billit API! This page will help you with the Billit API. You'll be up and running in a jiffy!

πŸ“ API Reference

The Billit API is built around the REST Principal. It uses easy to recognize URLs and it accepts JSON bodies as a basis to use the API. The responses you might get are always in the JSON format.

The API can be used in Test mode (Sandbox) and Full production. This allows you to fully build and test your use case risks-free. For basic API uses we allow an API Key. For more elaborate use cases or when the integration is built for multiple customers we require the integrator to use the OAuth flow.

If you provide your API key in the testing sections of this documentation it will only be visible to you. All test data shown to you when using your private key remains private.

:wrench: Sandbox VS Production

Billit has 2 environments for developers. You can find more info here Sandbox VS Production

:lock: Authentication


Secret Keys

Billit will never ask for any secret keys. Please do not send these to anyone since they could be a security risk. If any of these keys have been leaked please contact Billit so we can take action!

Billit supports two ways of API authentication: API keys and OAuth.

The use of the API Key and the use of Oauth:


The API key is an easy way to start using the API. You can find your unique key under the 'profile tab' -> 'Users & API key'. Please store it in a safe location and do not send it to anyone.

  • The API key setup is very basic. You provide it in the header of the API call.
    When using the API key for multiple companies you will have to provide a Company/PartyID. This
    is only mandatory when the user is linked to two or more companies, so the API call is directed
    to the correct company.

  • When executing an API call from an accountant account for one of its companies, you
    will have to set the ContextCompanyID of the accountant, and the PartyID of the company.

RequiredHeader field nameHeader field value
YesapiKey"The Super Secret Key"
Make sure the right context is usedpartyID123456
When using API calls for a company under an accountantcontextPartyID654321


At Billit we stand behind OAuth and actively promote it. It is not mandatory for personal use, but when an integration is going live for multiple users we do make this a requirement.

  • If you want to use OAuth you can send an email to [email protected] with the request for the OAuth Client ID and Secret. You will have to provide us with a Redirect URL and Integration Name. After providing our support with this information they will create the Credentials and send them to you.

  • These are only valid on Sandbox. For the ID and Secret to be generated on Production you will have to be approved for Production first.

πŸ’¬ We're here to help!

Ok, enough explaining. We hope you have a nice experience using our API.
What support can I get as a developer?

Also, make sure to have a look at our FAQ's. We've tried to explain everything to make sure you can start right away.

Good luck with your awesome integration. We're excited to see what you're going to build!