Deprecating GET requests to /translate and authenticating with auth_key

On or after March 14, 2025, DeepL will deprecate two little-used API features.

• You will no longer be able to send GET requests or query parameters to the /translate endpoint. Going forward, /translate will accept only POST requests with data included in the request body.

• You will no longer be able to authenticate a request to any endpoint by sending an API key in a query parameter. Instead, send your API key in an HTTP header named Authorization .

• If you use one of DeepL's officially-supported client libraries, you won't be negatively affected by the breaking changes and do not need to update your application. Specifically, we've confirmed the following client library versions:

  • deepl-php: 1.0.0+

  • deepl-python: 1.0.0+

  • deepl-java: 1.0.0+

  • deepl-dotnet: 1.0.0+

  • deepl-node: 1.1.0+

  • deepl-rb: 3.0.0+ (the first version where DeepL took over ownership of the Ruby client library)
    

You can find the full details in our developer documentation -> https://developers.deepl.com/docs/resources/breaking-changes-change-notices/march-2025-deprecating-get-requests-to-translate-and-authenticating-with-auth_key