1

Create an integration

Sign up for a free Nango account (here) if you haven’t already. Then navigate to Integrations -> Configure New Integration -> select Sellsy.
2

Authorize Sellsy (Client Credentials)

Go to Connections -> Add Test Connection -> Authorize, then enter your Sellsy Client Id and Secret shopper. 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 Sellsy (fetch a list of contacts). Replace the placeholders below with your Nango secret key, integration ID, and connection ID:
curl -X GET "https://api.nango.dev/proxy/v2/contacts" \
  -H "Authorization: Bearer <NANGO-SECRET-KEY>" \
  -H "Provider-Config-Key: <INTEGRATION-ID>" \
  -H "Connection-Id: <CONNECTION-ID>" \
  -H "Accept: application/json"
You can also 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.