# Idempotency key

A value sent with a request so that sending it again does not do the work again.

Send the same Idempotency-Key with a job request and Kaabist returns the job it already created instead of starting another one. Together with side-effect fences, it means a network error on your side never turns into a second submission on the website.

```
curl https://api.kaab.ist/v1/jobs \
  -H 'Authorization: Bearer $KAAB_API_KEY' \
  -H 'Idempotency-Key: claim-2026-10-10-0042' \
  -d '{"program": "file-claim@production", "inputs": {"claim_id": "0042"}}'
```

## Related

- [Never submits twice](/product/side-effects)
- [Forms that must submit exactly once](/use-cases/submit-exactly-once)
- [Side-effect fence](/glossary/side-effect-fence)