Claude API

Overview

The Claude API lets you embed Anthropic’s state-of-the-art Claude models (Opus, Sonnet, Haiku — and the latest Claude 4 generation) into any product through simple HTTP-JSON calls.

Key capabilities

• Chat & Vision – send mixed text-and-image messages and receive multimodal answers.
• Tool / Function Calling – define JSON-schema tools so Claude can invoke your functions programmatically.
• Extended & Interleaved Thinking – stream Claude’s step-by-step reasoning when you need deeper insight, or keep responses terse for speed.
• Files & Web Search – upload documents for grounded answers or let Claude query the live web.
• OpenAI-compatible endpoint – swap base-URL, model name and key to reuse existing OpenAI integrations.

Core endpoints

All requests require an anthropic-version header (e.g. 2023-06-01) and an x-api-key.

Recent additions

• May 2025 – Claude 4 models, Files API, code-execution tool.
• Feb 2025 – OpenAI-compatible endpoint, vision URL sources.
• May 2025 – Web search tool, fine-grained tool streaming.

Typical use-cases

• Conversational assistants & support bots
• Autonomous coding and data-analysis with Claude Code
• Document Q&A, summarization & RAG pipelines
• Agentic RPA workflows via Computer Use beta

Anthropic enforces strict safety policies (Constitutional AI) and rates Claude 4 Opus at AI Safety Level 3.

For full pricing, rate-limits and SDKs (Python, JS/TS, Go, Java, Ruby) see the official docs.