> ## Documentation Index
> Fetch the complete documentation index at: https://developers.1-funnel.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Idempotency

> Idempotency-Key usage for durable create operations.

<Warning>
  **Developer Preview**

  This documentation describes the upcoming 1Funnel External Integration API.

  The documented API endpoints and authentication services are not yet available
  for public integration.

  You can explore the API specifications, request and response schemas, webhook
  events, and integration guides.

  Sandbox and production availability will be announced separately.
</Warning>

Mutating create operations that accept an `Idempotency-Key` header treat the
key as a durable client-supplied uniqueness token for the documented retention
window. Replays with the same key and equivalent body return the original
acceptance result rather than creating a duplicate resource.

Use a new key for intentionally new work. See
[API reference: Idempotency](/api-reference/idempotency).


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