Idempotency & Rate Limits

Duplicate prevention: Both collection and transfer requests use a userTransactionRef (reference) to prevent duplicate transactions. If you don't provide one, Startbutton generates a unique reference for you. If you provide one that's already been used, the request is rejected with a duplicate error. Your reference is returned in the webhook response as userTransactionRef.

Rate limits: All Startbutton API endpoints are limited to 1000 requests per minute.