SDKs, CLI, and libraries

SDKs, CLI, and libraries

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Official tools for building with the Claude API: client SDKs in seven languages, the ant CLI, and framework-specific libraries.

Anthropic provides three kinds of official tooling for building with the Claude API:

• CLI: The ant command-line tool for shell scripting and interactive use.
• Client SDKs: General-purpose Messages API clients for Python, TypeScript, C#, Go, Java, PHP, and Ruby. Each SDK provides idiomatic interfaces, type safety, and built-in support for streaming, retries, error handling, and OpenTelemetry tracing.
• Libraries and integrations: Packages and compatibility layers that expose Claude inside another framework's API surface rather than the Messages API directly.

CLI

Client SDKs

Each major version of a client SDK sends one API version by default, and a new major version comes with each new API version. To move to 2026-10-21, see Switch to 2026-10-21.

Latest versions

The same versions are available as JSON at https://platform.claude.com/docs/sdk-versions.json.

Libraries and integrations

Libraries and integrations expose Claude through another framework's API surface. They are not general-purpose Messages API clients.

Building agents or using Claude Code?

The CLI, client SDKs, and libraries are for calling the Claude API yourself: you send each request and handle each response. Claude Code, the Claude Agent SDK, and Claude Managed Agents work at a higher level, providing the agent loop, tool execution, and runtime.