> ## 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.

# API versioning

> REST path versioning and webhook event versioning.

<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>

* REST paths are versioned under `/v1/...`.
* Webhook envelopes use `api_version: "v1"`.
* Event types carry a suffix such as `.v1` (for example `sms.message.delivered.v1`).

Within an existing event `.v1`, only additive optional fields are compatible.
Breaking event changes require a new event type/version. See the webhook
[event compatibility](/guides/webhooks/event-compatibility) guide.


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