CLI, SDKs, and libraries
Official tools for building with the Claude API: the ant CLI, client SDKs in seven languages, and framework-specific libraries.
Anthropic provides three kinds of official tooling for building with the Claude API:
- CLI: The
antcommand-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.
CLI
Shell scripting, typed flags, response transforms
Client SDKs
Sync and async clients, Pydantic models
Node.js, Deno, Bun, and browser support
.NET Standard 2.0+, IChatClient integration
Context-based cancellation, functional options
Builder pattern, CompletableFuture async
Value objects, builder pattern
Sorbet types, streaming helpers
Libraries and integrations
Libraries and integrations expose Claude through another framework's API surface. They are not general-purpose Messages API clients.
Swift package for Apple's LanguageModelSession API
Use Claude through the OpenAI SDK surface
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.
Agentic coding tool for delegating coding tasks to Claude
Build agents that run in a process you operate
Run agents in Anthropic's managed infrastructure
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