Handle Stripe idempotency key expiry and collision edge cases in high-throughput payment systems

In-depth guide

Steps

1. Understand that Stripe caches idempotency key results for 24 hours after the first successful request; after expiry, reusing the same key with different parameters will create a new request rather than returning a cached result.
2. Generate idempotency keys that are globally unique per logical payment attempt: incorporate customer ID, order ID, and attempt number to avoid accidental collisions across retries for different orders.
3. Handle the 'IdempotencyError' (status 422) that Stripe returns when an idempotency key is reused within the cache window with different request parameters — log and alert on this, as it indicates a key-generation bug.
4. For asynchronous job queues, bind the idempotency key to the job ID rather than generating a fresh key on each dequeue, ensuring that redelivered jobs do not create duplicate charges.
5. After a network timeout (no HTTP response received), always retry with the original idempotency key rather than generating a new one — this is the primary protection against double-charges.
6. Periodically audit your idempotency key generation logic in load tests to confirm uniqueness under concurrent request conditions.