The API supports idempotency for safely retrying requests without accidentally performing the same operation twice. This is useful when an API call is disrupted in transit and you do not receive a response. For example, if a request to create a charge does not respond due to a network connection error, you can retry the request with the same idempotency key to guarantee that no more than one charge is created.
To perform an idempotent request, provide an additional idempotency-key: header to the request.
An idempotency key is a unique value generated by the client which the server uses to recognize subsequent retries of the same request. How you create unique keys is up to you, but we suggest using V4 UUIDs, or another random string with enough entropy to avoid collisions. Idempotency keys can be up to 255 characters long.
When an idempotecy key is provided and the key has already been used in a previous request, the request will respond with a 400.