[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"glossary-idempotency::en":3,"gloss-cluster-idempotency::en":20,"gloss-next-idempotency::en":9},{"slug":4,"category":5,"name":6,"definition":7,"meta_desc":8,"faq":9,"schema_markup":9,"related":10},"idempotency","dev-tools","Idempotency","Idempotency is a property of an operation where performing it multiple times has the exact same effect as performing it once — calling the operation again doesn't change the outcome or cause unintended side effects beyond the first call. It's a critical concept for any system that involves network calls, because networks are inherently unreliable: a request can time out or a response can get lost even though the operation actually succeeded on the server, and the only safe way to handle that uncertainty is to retry — but retrying is only safe if the operation is idempotent, otherwise a retried \"charge $50\" request could charge the customer twice. Why it matters for AI\u002FSaaS builders: idempotency is foundational to reliable payment processing, webhook handling, and any AI agent system that can take real-world actions with retries built in — an agent (or a distributed system generally) that retries a failed tool call needs a guarantee that the retry won't duplicate a real-world effect like sending a duplicate email, double-charging a card, or creating two support tickets for the same issue. Stripe's API is a widely-cited real-world example: it requires an `Idempotency-Key` header on charge-creation requests specifically so a client can safely retry a request that timed out without risking a duplicate charge. How it works: idempotency is typically implemented by having the client generate a unique key for a given logical operation (often a UUID) and send it with the request; the server checks whether it has already processed a request with that exact key — if so, it returns the same result as the original successful call without re-executing the underlying side effect (charging the card, sending the email); if not, it processes the request normally and records the key alongside the result for a period of time, so any retry with the same key is safely recognized. Naturally idempotent operations (like `PUT \u002Fusers\u002F42 {name: \"Alex\"}` — setting a field to a specific value repeatedly always results in the same final state) don't need this mechanism explicitly; naturally non-idempotent operations (like `POST \u002Forders` creating a new order, or an increment operation) do. Worked example: a checkout flow calls `POST \u002Fcharges` with `Idempotency-Key: a1b2c3-order-9284` to charge a customer $49. The request reaches the payment processor, the charge succeeds, but the network connection drops before the success response reaches the client. The client's code, seeing what looks like a failed request, automatically retries the exact same `POST \u002Fcharges` call with the identical idempotency key. The payment processor recognizes the key has already been used for a successful charge, does not charge the card a second time, and simply returns the original success response — the customer is charged exactly once despite the retry, purely because the operation was designed to be idempotent.","Idempotency means performing the same operation multiple times produces the same result as performing it once — critical for safe retries.",null,[11,14,17],{"slug":12,"name":13},"agent","Agent",{"slug":15,"name":16},"api-gateway","API Gateway",{"slug":18,"name":19},"webhook-dev-tools","Webhook",[21,23,26,28,31,34,37,40,43,46,49,52],{"slug":12,"category":5,"name":13,"updated_at":22},"2026-08-24T02:46:36+00:00",{"slug":24,"category":5,"name":25,"updated_at":22},"ai-code-assistant","AI Coding Assistant",{"slug":15,"category":5,"name":16,"updated_at":27},"2026-08-24T02:46:37+00:00",{"slug":29,"category":5,"name":30,"updated_at":27},"api-versioning","API Versioning",{"slug":32,"category":5,"name":33,"updated_at":22},"autonomous-agent","Autonomous Agent",{"slug":35,"category":5,"name":36,"updated_at":27},"blue-green-deployment","Blue-Green Deployment",{"slug":38,"category":5,"name":39,"updated_at":27},"canary-deployment","Canary Deployment",{"slug":41,"category":5,"name":42,"updated_at":27},"chaos-engineering","Chaos Engineering",{"slug":44,"category":5,"name":45,"updated_at":22},"ci-cd","Continuous Integration \u002F Continuous Deployment (CI\u002FCD)",{"slug":47,"category":5,"name":48,"updated_at":27},"circuit-breaker","Circuit Breaker",{"slug":50,"category":5,"name":51,"updated_at":27},"cli","Command-Line Interface (CLI)",{"slug":53,"category":5,"name":54,"updated_at":27},"cloud-development-environment","Cloud Development Environment (CDE)"]