Developers

The API, webhooks, payment and payout statuses, and error codes.

• How do I verify Fynex webhook signatures?Every webhook is signed. Recompute an HMAC-SHA256 of the timestamp and raw body with your signing secret, compare it to the X-Fynex-Signature header, and reject anything older than 5 minutes.
• Which webhook events does Fynex send?Fynex sends events for payments, payment links, subscriptions, promo codes, and business verification. Each has the same envelope, is signed, and retries up to 3 times to allowlisted URLs.
• How do idempotency keys work?Send a unique idempotency key with a request so a retry can't create a duplicate. Reusing a key returns the original result instead of acting twice — essential for payouts.
• Payment statuses referenceThe statuses a payment moves through, from created to settled, plus the refund and failure states — with what each one means for your integration.
• Payout statuses and failure codes referenceThe statuses a payout moves through, the approval state, and the failure codes you may receive — each with a customer-safe meaning.
• How do I test subscriptions with the test clock?A test clock lets you fast-forward time in test mode so you can see a subscription's renewals, trial ending, and dunning without waiting real days.
• Payment Links API quickstartCreate a payment link over the REST API, share the hosted URL, and receive a webhook when it's paid. Authenticate with your seller account token.