# The auth_key body field stops working

Calls to body parameter auth_key on DeepL API stopped working on January 15, 2026.

- API: DeepL API (api.deepl.com)
- Kind: Endpoint removal
- Takes effect: January 15, 2026
- Calls after that day: fail
- Calls it hits: `body parameter auth_key`
- Source: [Announcement](https://developers.deepl.com/docs/resources/breaking-changes-change-notices/november-2025-deprecation-of-legacy-auth-methods)
- Page: https://www.okapi.bot/providers/deepl-api/breaking-changes/the-auth-key-body-field-stops-working/

## What to use instead

Send the key in the Authorization header: Authorization: DeepL-Auth-Key [yourAuthKey].

## DeepL API's words

> Update: The deadline for this deprecation has been extended to January 15th, 2026.