---
title: "Deprecations"
url: "https://docs.unified.to/reference/deprecations"
description: "How the API signals deprecated endpoints and fields"
updated: "2026-10-16T18:18:45.000Z"
---
# Deprecations

Updated: October 16, 2026

The API signals deprecations in machine-readable ways so that your code — and AI agents building against the API — can detect them automatically, rather than relying on you to read a changelog.

## [Response headers](https://docs.unified.to/reference/deprecations.md#response-headers)

When you call a deprecated endpoint, the response carries standard deprecation headers:

| Header      | Standard                                           | Description                                                                                                                             |
| ----------- | -------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| Deprecation | [RFC 9745](https://www.rfc-editor.org/rfc/rfc9745) | Present with the value true when the endpoint is deprecated.                                                                            |
| Sunset      | [RFC 8594](https://www.rfc-editor.org/rfc/rfc8594) | An HTTP date after which the endpoint may stop responding. Present only when a date has been set.                                       |
| Link        | —                                                  | A link to the replacement, with rel="successor-version", e.g. Link: </accounting/{connection\_id}/salesorder>; rel="successor-version". |

Watch for the `Deprecation` header in your responses and migrate to the resource named by the `Link` successor before the `Sunset` date, if one is given.

## [Specification flags](https://docs.unified.to/reference/deprecations.md#specification-flags)

Deprecated operations and fields are also marked in our [OpenAPI and Swagger specifications](https://docs.unified.to/reference/sdks.md) with the standard `deprecated: true` flag. Code generators (including the ones that build our [SDKs](https://docs.unified.to/reference/sdks.md)) surface these as deprecation warnings, so deprecated fields and methods are flagged in your editor at build time.

Avoid deprecated operations and fields in new code, and prefer the successor the specification or the `Link` header points to.