Documentation - Claude Platform Docs Claude PlatformStart building with Claude Everything you need to integrate Claude into your applications. From first API call to production. SearchCtrlK QuickstartGet API keyAPI reference PythonTypeScriptGoJavaRubyPHPC#cURLCLI  import anthropic client = anthropic.Anthropic() message = client.messages.create( model="claude-opus-5", max_tokens=1024, messages=[{ "role": "user", "content": "Hello, Claude" }] ) for block in message.content: if block.type == "text": print(block.text) Platform Choose how you build Pick the developer surface that matches your approach, and the infrastructure that fits your stack. Messages Direct model access. You construct every turn, manage conversation state, and write your own tool loop. QuickstartAPI referenceClient SDKs Managed Agents Fully managed agent infrastructure. Deploy and manage autonomous agents in stateful sessions with persistent event history. QuickstartAPI referenceDefine your agent Claude is also available on these cloud platforms: Amazon Bedrock Google Cloud Microsoft Foundry Developer journey From idea to production Follow the lifecycle or jump to what you need. MessagesManaged Agents 1 Get started Quickstart Get API key Choose a model Install an SDK Try the Workbench 2 Build Messages API Thinking Vision Tool use Web search Code execution Structured outputs Prompt caching Streaming 3 Evaluate and ship Prompting best practices Run evals Batch testing Safety and guardrails Rate limits and errors Cost optimization 4 Operate Workspaces and admin API key management Usage monitoring Model migration Models The Claude model family Choose the right model for your use case. Most capableFable 5 claude-fable-5 Highest capability for the most demanding reasoning and long-horizon agentic work. AdvancedOpus 5 claude-opus-5 Excellent for complex analysis, coding, and creative tasks requiring deep reasoning. Best balanceSonnet 5 claude-sonnet-5 Ideal balance of intelligence and speed for most production workloads. FastestHaiku 4.5 claude-haiku-4-5 Lightning-fast responses for high-volume, latency-sensitive applications. Resources Keep learning Courses Interactive courses to master Claude. Cookbook Code samples and patterns. Quickstarts Deployable starter apps. What's new Latest features and updates. Claude Code An agentic coding assistant in your terminal.