# Anthropic updates API and SDKs to version 2026-10-21

> New API version released with updated client libraries and a license change for the SDKs and CLI.

Oossa · 2026-10-21 · https://oossa.com/en/anthropic-updates-api-and-sdks-to-version-2026-10-21

Event date: 2026-10-21

Anthropic announced on October 21, 2026 that its API now uses version 2026-10-21. The company also released fresh client SDKs for Python, TypeScript, C#, Go, Java, PHP, Ruby and an updated ant CLI, all set to send the new API version by default. These SDK and CLI updates introduce breaking changes unrelated to the API itself and switch their license from MIT to Apache 2.0.

## The facts

- API version 2026-10-21 released on 2026-10-21.
- SDKs and CLI now under Apache 2.0 license.

## Why it matters

Developers using Anthropic’s services must upgrade their code to the new SDKs and adapt to breaking changes, or risk incompatibility with the latest API.

## Sources & references

1. [docs.anthropic.com: October 21, 2026](https://docs.anthropic.com/en/release-notes/api#october-21-2026) – Anthropic API, 2026-10-21

Last updated: 2026-10-21