Why Blind API Retries Cause Duplicate Operations and How Idempotency Keys Prevent Them

The article explains that a request timing out does not reveal whether the server processed it, so retrying it blindly can cause duplicate actions such as double payments or repeated orders. It notes that network failures are unavoidable but duplicate operations are preventable. HTTP treats PUT, DELETE, and GET as idempotent, while POST is not, so clients should not automatically retry it without extra safeguards. To address this, developers can attach a unique Idempotency Key to each logical operation, allowing the server to recognize and reuse the stored result of a repeated request. The piece also recommends combining this approach with controlled retries using exponential backoff and jitter.