When we say that an action is “idempotent”, the effect of that action will be the same EVERY TIME we perform it. When an API request is idempotent, the state of our system1 will be the same in subsequent requests.
| HTTP Method | Idempotent | Safe |
|---|---|---|
GET | ✅ | ✅ |
HEAD | ✅ | ✅ |
PUT | ✅ | ❎ |
DELETE | ✅ | ❎ |
POST | ❎ | ❎ |
PATCH | ❎ | ❎ |
Resources
- https://www.rfc-editor.org/rfc/rfc9110.html#name-idempotent-methods
- https://restfulapi.net/idempotent-rest-apis/
- https://stackoverflow.com/questions/4088350/is-rest-delete-really-idempotent
Footnotes
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I had to emphasize this because I saw a lot of definitions of Idempotency when I was searching for it and there a lot of them are focusing on the result of the request, which is not really what the standard says: “intended effect on the server of multiple identical requests” ↩