What does "idempotency" mean in programming?
idempotency is one of the most common terms in software development. This guide explains what it means, how it is used in practice, and why it matters, with real examples from the developer world.
Definition
The property of an operation that produces the same result whether applied once or many times. In HTTP, GET, PUT, and DELETE are idempotent; POST is usually not. Idempotent APIs are safe to retry on failure without risking double-execution.
Example
"Make the payment endpoint idempotent — retrying a duplicate request must not charge the user twice."
Word forms
| Form | Type | Meaning | Example |
|---|---|---|---|
| idempotent | adjective | Producing the same result regardless of how many times applied | "PUT requests should be idempotent — applying the same update twice must not double-charge a user." |
Related terms
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