DevOps Glossary

Idempotency Key is a unique value sent with an API request so the server can identify repeat attempts of the same operation and avoid duplicate side effects, such as creating two orders, charging a card twice, or provisioning the same resource more than once. Clients commonly include the key in a header, then reuse the same key when retrying after a timeout, network failure, or unclear response. The server stores the key with the original request result for a limited time and returns the same result for matching retries. Idempotency keys are especially useful for payment APIs, order creation, account setup, and other write operations where “try again” should not mean “do it twice.”