> ## 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.

# Event compatibility

> Additive evolution rules for webhook event payloads.

<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>

Within an existing event type `.v1`:

* Adding optional fields is compatible
* Consumers must ignore unknown optional fields

Breaking changes (new required fields, renames, type changes, enum removals,
envelope changes) require a new event type/version and separate approval.

Envelope `api_version` remains `v1`. Ordering tokens are not part of the contract.


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