CLI, SDKs, and 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, and error handling.
• Libraries and integrations: Packages and compatibility layers that expose Claude inside another framework's API surface rather than the Messages API directly.

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CLI

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Client SDKs

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Libraries and integrations

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

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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.