Claude API

Anthropic's New SDKs Can Drop Your API Key Behind a Gateway

On 21 October Anthropic released API version 2026-10-21, the first since 2023-06-01, with new SDK majors (Python 2.0.0, TypeScript 1.0.0, Go 2.0.0, Java 3.0.0, C# 13.0.0, PHP 1.0.0, Ruby 2.0.0, ant CLI 2.0.0) that send it by default and on which temperature, top_p and top_k return a 400 even at default values. The SDKs also move the API key from X-Api-Key into Authorization: Bearer. On a local capture server, a gateway token set in that header through default_headers replaced the key outright with no error; the guide's fix (auth_token plus X-Api-Key in default_headers, with the gateway stripping its own Authorization) and the undocumented version pin (default_headers anthropic-version 2023-06-01 plus extra_body temperature) both produced the expected request. LiteLLM reads Authorization before x-api-key, so its virtual keys still arrive.