Latest stable Anthropic Python SDK: 2.3.0, released (release notes). 202 stable releases since 8 Jan 2024.
anthropic-version: 2026-10-21
The third version of the Claude API, after 2023-01-01 and 2023-06-01. Requests sent with an older SDK keep the version that SDK was built for.
- 202stable releases since Jan 2024
- 3days between stable releases, median
- 13in Jun 2026, the busiest month
- 53days, the longest wait (28 Feb 2025 to 22 Apr 2025)
POST /v1/messages- anthropic-version: 2023-06-01+ anthropic-version: 2026-10-21# request body- "temperature"400 on every model- "top_p"400 on every model- "top_k"400 on every model- assistant → document block400; send it in a user message- user → text with citations400# Admin and Analytics API responses- roles+ role_ids- group_id+ rbac_group_id- name+ display_name- group_type+ group.type- workspace_id+ scope.workspace_id- actor.email+ actor.email_addressMajors released 21 October
- Python
2.0.0 - TypeScript
1.0.0 - Go
2.0.0 - Java
3.0.0 - Ruby
2.0.0 - PHP
1.0.0 - C#
13.0.0 - ant CLI
2.0.0
License: MIT Apache 2.0
On 21 October 2026 Anthropic released API version 2026-10-21, the first new value for the anthropic-version header since 2023-06-01, 1,238 days earlier, and only the third version the API has had. The same day it published new major versions of every client SDK and the ant CLI that send it by default: Python 2.0.0, TypeScript 1.0.0, Go 2.0.0, Java 3.0.0, Ruby 2.0.0, PHP 1.0.0, C# 13.0.0 and ant 2.0.0, all now licensed under Apache 2.0 instead of MIT.
Under the new version, temperature, top_p and top_k are removed and return a 400 error on every model, as do document blocks placed directly in assistant messages and citations on text in user messages. Six Admin and Analytics API fields are renamed. On Amazon Bedrock the new version only works with Claude 4.7 and later models. The Python SDK reached 1.0.0 only on 20 August, when it moved to httpx2, and has shipped 22 releases since; Claude Code 2.1.307 added /claude-api api-version to move code to the new version.
As of 24 October 2026. Migrating to API version 2026-10-21.
Latest Python SDK releases
2.3.0Claude Tag endpoints for Claude Enterprise; Google Cloud user profiles fix.2.2.0Message threads; usage and cost reports by dimension.2.1.0Enforcement status and actions on user profiles.2.0.0Sends API version 2026-10-21 by default; Apache 2.0.1.17.0Org webhook endpoints; RBAC group owner-access errors.1.16.0Workspace rate-limit updates in the Admin API.
From @claudeai on X
Claude Models on Google Cloud (Anthropic managed) is now generally available.
Get the full set of Claude Platform features on Google Cloud, with Google Cloud IAM credentials, billing, and commitment retirement.
Google Cloud is one of the platforms where 2026-10-21 is available; Python SDK 2.3.0 fixed its user profiles endpoint two days after the version shipped.
