Partner API Client ID and Client Secret — issued by BigChange to the integrator (set once per Nango integration).
Customer ID — the numeric Customer ID for the BigChange tenant you are connecting (per Nango connection).
BigChange uses OAuth 2.0 Client Credentials authentication: a single Partner API client_id and client_secret are configured at the Nango integration level, and each individual BigChange customer is identified by their numeric Customer ID, passed in the customer-id request header.
Click Create new API Key, give it a descriptive name, and confirm. BigChange will issue a client_id and client_secret.
Copy both values. The client_secret is shown only once.
In your Nango BigChange integration settings, paste the client_id and client_secret into the Client ID and Client Secret fields. These are shared across every BigChange tenant you connect.