Idempotency
Safe retries with Idempotency-Key on create and cancel.
Idempotency
Every request that creates or moves money accepts an Idempotency-Key header. Send a unique value (a UUID is fine) per logical operation. If a request is retried with the same key, the original response is replayed instead of the operation running twice.
Use this on every create call. Network timeouts do not tell you whether the request succeeded, and retrying without a key can create duplicate payment links.
Rules
| Rule | Detail |
|---|---|
| Scope | Per API key |
| Retention | 24 hours |
| Replay header | Idempotent-Replayed: true on replayed responses |
| Same key, different body | 422 (idempotency_key_reused) |
| Original still running | 409 (idempotency_request_in_progress) — retry after a short delay |
| 5xx responses | Not stored — retrying runs the request again |
Example
curl -X POST https://stggateway-sandbox.momen.co/v1/payment-links \-H "Authorization: Bearer sk_test_YOUR_KEY" \-H "Content-Type: application/json" \-H "Idempotency-Key: 8f14e45f-ceea-467a-9575-8f14e45fceea" \-d '{ "amount": 150000, "title": "Invoice #1042"}'reference_id is not used for idempotency. Use Idempotency-Key for that.