> ## Documentation Index
> Fetch the complete documentation index at: https://docs.clemta.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Versioning

> How the Partner API versions its contract by date

The Partner API is versioned by date. A breaking change ships as a new dated
version, and the version you integrated against keeps working unchanged.

## Picking a version

Every request resolves to exactly one version, in this order:

1. The `Clemta-Version` header, if you send one.
2. Your account default, pinned the first time you created a key.
3. The latest version, if neither of the above applies.

Send the header to pin a request explicitly:

```
Clemta-Version: 2026-08-13
```

The effective version is echoed back on every response in the same header, so
you can always confirm which contract answered you.

## What a version pins

A dated version pins the request and response shapes and the set of error
codes. When a new version renames or restructures a field, the old version
still answers with the old shape. Your integration does not have to move until
you choose to.

An unknown version is rejected with `invalid_api_version`. Use a date the
[API versions](/partner/versions) page lists, or omit the header to run on your
account default.

## Deprecation and sunset

A version can be deprecated once a newer one supersedes it. It keeps answering
until a published sunset date, but every response on it carries two headers:

* `Deprecation` marks the version as deprecated.
* `Sunset` is the date after which it may stop answering.

You can detect this from traffic alone, without polling the docs. The
[API versions](/partner/versions) page lists any deprecation schedule.
Move to the current version before the sunset date to avoid disruption.

## Webhooks are versioned too

The events we deliver to your endpoint are versioned the same way. Each delivery
is rendered at the webhook version set for your workspace, so a payload keeps its
shape even as newer API versions restructure the same resource. The event's
`data.object` therefore matches the version you integrated against, not
necessarily the latest one. Set your webhook version in the dashboard. It
defaults to the API version pinned on your account.

## Downloading the spec

Every version's full OpenAPI description is served for download, so you can
generate a client or diff two versions. See
[OpenAPI specs](/partner/openapi-specs) for the version-resolving and
frozen dated URLs.