Anthropic Claude API Client for Rust

Production-ready Rust client for Anthropic's Claude API with 83% feature coverage

A comprehensive, feature-rich HTTP client for interacting with Anthropic's Claude API. Built with safety, performance, and developer experience in mind.

✨ Features

• 💬 Messages API - Full conversational interface support
• 💾 Prompt Caching - ~90% cost savings with Anthropic's caching
• 📡 Streaming - Server-Sent Events (SSE) streaming responses
• 🛠️ Tool Calling - Complete function calling and tool integration
• 🖼️ Vision Support - Image analysis capabilities
• 📊 Enterprise Ready - Rate limiting, retries, circuit breaker, failover
• 🔍 Rich Diagnostics - Curl command generation and detailed error context
• 🔄 Sync & Async APIs - Both synchronous and asynchronous interfaces

🚀 Quick Start

Add to your Cargo.toml:

[dependencies]
api_claude = { version = "0.1.0", features = ["full"] }

Basic Usage

use api_claude::{ Client, Secret, CreateMessageRequest, Message, Role, Content };

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create client with API key
    let secret = Secret::new("sk-ant-api03-your-key-here".to_string())?;
    let client = Client::new(secret);

    // Create a message request
    let request = CreateMessageRequest::builder()
        .model("claude-sonnet-4-5-20250929".to_string())
        .max_tokens(1000)
        .messages(vec![
            Message {
                role: Role::User,
                content: vec![Content::Text {
                    r#type: "text".to_string(),
                    text: "Hello, Claude! How are you?".to_string(),
                }],
                cache_control: None,
            }
        ])
        .build();

    // Send request and get response
    let response = client.create_message(request).await?;
    println!("Claude: {:?}", response.content);

    Ok(())
}

🔧 Configuration

Set your API key via environment variable:

export ANTHROPIC_API_KEY="sk-ant-api03-your-key-here"

Or use workspace secrets (see Secret Loading Guide).

📚 Documentation

• API Reference - Complete API documentation
• Examples - Real-world usage examples
• Testing Guide - Testing organization and NO MOCKING policy
• Secret Loading - Authentication and secret management
• Specification - Detailed project specification

🏗️ Project Structure

api_claude/
├── src/          # Library source code
├── tests/        # Comprehensive test suite (435 tests)
├── examples/     # Usage demonstrations
├── docs/         # Architecture and design documentation
└── spec.md       # Project specification

🧪 Testing

# Run all tests
cargo nextest run --all-features

# Run with linting
cargo clippy --all-targets --all-features -- -D warnings

# Documentation tests
cargo test --doc --all-features

⚠️ Note: Integration tests require valid ANTHROPIC_API_KEY and use real API calls (NO MOCKING).

🔧 Building

# Build with all features
cargo build --all-features

# Build for release
cargo build --release --all-features

📋 Feature Flags

Fine-grained control via feature flags:

• authentication - API key management
• rate-limiting - Token bucket rate limiting
• retry-logic - Request retry mechanisms
• circuit-breaker - Circuit breaker pattern
• streaming - SSE streaming support
• full - All features enabled

See Cargo.toml for complete list.

📝 License

This project is licensed under the MIT License.

🤝 Contributing

Contributions welcome! Please ensure all tests pass before submitting PR.