An idempotency key binds one business command to one result. Reuse it when you repeat the same request after a timeout.
Send a stable key
Derive the value from your system ID and action. Do not create a random timestamp for a retry of the same command.
Keep the same body
SimplePay compares the request fingerprint. The same key with different parameters returns a conflict.
Reuse the key for timeouts, 429, and retryable errors. Correct validation failures before sending another command. Last modified on August 22, 2026
