1

Create an integration

In Nango (free signup), go to Integrations -> Configure New Integration -> Sellsy. Nango doesn’t provide a test OAuth app for Sellsy yet. You’ll need to set up your own by following these instructions. After that, make sure to add the OAuth client ID, Secret shopper, and scopes in the integration settings in Nango.
2

Authorize Sellsy

Go to Connections -> Add Test Connection -> Authorize, then log in to Sellsy. Later, you’ll let your users do the same directly from your app.
3

Call the Sellsy API

Let’s make your first request to the Sellsy API (fetch a list of contacts). Replace the placeholders below with your secret key, integration ID, and connection ID:
curl "https://api.nango.dev/proxy/v2/contacts" \
  -H "Authorization: Bearer <NANGO-SECRET-KEY>" \
  -H "Provider-Config-Key: <INTEGRATION-ID>" \
  -H "Connection-Id: <CONNECTION-ID>"
Or fetch credentials dynamically via the Node SDK or API.
✅ You’re connected! Check the Logs tab in Nango to inspect requests.
Next step: Embed the auth flow in your app to let your users connect their Sellsy accounts.
Questions? Join us in the Slack community.