Payments glossary
What is an idempotency key?
An idempotency key is a unique value sent with an API request so that, if the request is retried, the server returns the original result instead of performing the action twice.
It is essential for payment APIs: a network timeout followed by a retry must never create two charges or two refunds.
How it works in Allidian
Allidian's API accepts an Idempotency-Key header on money-moving requests and replays the original response for repeated keys.