An idempotent API is an API that can be called multiple times with the same input parameters and produces the same result every time. In other words, calling an idempotent API multiple times with the same inputs should have the same effect as calling it once.
This is a desirable property for APIs that perform operations that are meant to be idempotent, meaning that they can be repeated multiple times without causing unintended side effects.
For example, consider an API that deletes a resource from a database. If the API is idempotent, then calling it multiple times with the same input (the ID of the resource to be deleted) should delete the resource the first time, and have no effect on subsequent calls.
To make an API idempotent, it is important to ensure that the API’s implementation is deterministic and does not have any side effects that are not idempotent. This means that the API should not modify any state outside of its own scope, and that it should always return the same result for the same input.
In practical terms, an idempotent API should be designed so that a client can retry a request that fails due to a network error or other transient issue without worrying about unintended side effects. For example, if a client sends a request to an idempotent API and does not receive a response due to a network error, it should be safe to retry the request without worrying about unintended side effects.
Overall, idempotent APIs are useful in many scenarios where repeatable, reliable, and predictable behavior is required.