stripe-webhook-signature-verification

To verify a Stripe webhook signature in Node.js, you validate the HMAC-SHA256 signature in the stripe-signature header against your STRIPE_WEBHOOK_SECRET using the constructEvent flow. This requires passing the raw, unparsed request body to ensure the cryptographic check succeeds.

Stripe webhook verification fails in Next.js App Router when the request body is parsed before signature validation. You must access the raw, unparsed request body to use Stripe's constructEvent method, as JSON parsing alters the payload and breaks the HMAC-SHA256 signature match.

Stripe webhook replay protection works by enforcing a timestamp tolerance window on incoming events. This mechanism rejects stale or previously delivered webhook requests, preventing attackers from replaying old payloads to trigger duplicate payment processing.

Yes, you should handle idempotency even when verifying Stripe webhooks to prevent double-processing retries. Using the event.id pattern allows your handler to safely process retried webhook deliveries without duplicating payment routing or side effects.

When Stripe webhook signature verification cannot be completed, the handler cleanly fails by returning a 400 response. This blocks unauthenticated or tampered webhook requests from triggering any downstream payment processing or routing logic.

Yes, this Stripe webhook signature verification applies to any Node.js or Next.js backend handler. It requires frameworks that allow raw, unparsed request body access to successfully execute the constructEvent validation against the STRIPE_WEBHOOK_SECRET.