Which of the HTTP methods — POST, PUT, or PATCH — can be considered idempotent?

HTTP methods considered idempotent are those that can be called multiple times in a row with the same effect on the server, without changing the result after the first call.

• PUT — idempotent. Usually used to replace a resource entirely. Repeated requests with the same content will not further modify the resource.
• PATCH — not necessarily idempotent. It is intended for partial updates of a resource, and its idempotency depends on the implementation.
• POST — not idempotent. Used for creating resources or performing operations that may lead to different results upon repeated calls (e.g., creating multiple records).

In summary:

• PUT — idempotent
• PATCH — may be idempotent, but not guaranteed
• POST — not idempotent