x402 Rust Implementation

A high-performance, type-safe Rust implementation of the x402 HTTP-native micropayment protocol.

Features • Quick Start • Examples • Documentation

📦 Installation

Add this to your Cargo.toml:

[dependencies]
rust-x402 = "0.1.0"

✨ Features

• 🚀 HTTP-native micropayments: Leverage the HTTP 402 status code for payment requirements
• ⛓️ Blockchain integration: Support for EIP-3009 token transfers with real wallet integration
• 🌐 Web framework support: Middleware for Axum, Actix Web, and Warp
• 💰 Facilitator integration: Built-in support for payment verification and settlement
• 🔒 Type safety: Strongly typed Rust implementation with comprehensive error handling
• 🧪 Comprehensive testing: 62+ tests with 100% pass rate covering all real implementations
• 🏗️ Real implementations: Production-ready wallet, blockchain, and facilitator clients

🚀 Quick Start

Creating a Payment Server with Axum

use axum::{
    extract::State,
    http::StatusCode,
    response::Json,
    routing::get,
    Router,
};
use rust_x402::{
    axum::PaymentMiddleware,
    types::{PaymentRequirements, FacilitatorConfig},
};
use std::sync::Arc;

#[tokio::main]
async fn main() {
    // Create facilitator config
    let facilitator_config = FacilitatorConfig::default();
    
    // Create payment middleware
    let payment_middleware = PaymentMiddleware::new(
        rust_decimal::Decimal::from_str("0.0001").unwrap(),
        "0x209693Bc6afc0C5328bA36FaF03C514EF312287C".to_string(),
    )
    .with_facilitator_config(facilitator_config)
    .with_description("Premium API access".to_string());

    // Create router with payment middleware
    let app = Router::new()
        .route("/joke", get(joke_handler))
        .layer(payment_middleware);

    // Start server
    let listener = tokio::net::TcpListener::bind("0.0.0.0:4021").await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

async fn joke_handler() -> Result<Json<serde_json::Value>, StatusCode> {
    Ok(Json(serde_json::json!({
        "joke": "Why do programmers prefer dark mode? Because light attracts bugs!"
    })))
}

💳 Making Payments with a Client

use rust_x402::client::X402Client;
use rust_x402::types::{PaymentPayload, PaymentRequirements};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = X402Client::new();
    
    // Make a request to a protected resource
    let response = client.get("http://localhost:4021/joke").await?;
    
    if response.status() == 402 {
        // Handle payment required response
        let payment_req = response.json::<PaymentRequirements>().await?;
        
        // Create and sign payment payload (implementation depends on wallet integration)
        let payment_payload = create_payment_payload(&payment_req)?;
        
        // Retry request with payment
        let final_response = client
            .get("http://localhost:4021/joke")
            .header("X-PAYMENT", encode_payment_payload(&payment_payload)?)
            .send()
            .await?;
            
        println!("Response: {}", final_response.text().await?);
    }
    
    Ok(())
}

🏗️ Architecture

The Rust implementation is organized into several modules:

• 📦 types: Core data structures and type definitions
• 🌐 client: HTTP client with x402 payment support
• 💰 facilitator: Payment verification and settlement
• 🔧 middleware: Web framework middleware implementations
• 🔐 crypto: Cryptographic utilities for payment signing
• ❌ error: Comprehensive error handling
• 🏦 wallet: Real wallet integration with EIP-712 signing
• ⛓️ blockchain: Blockchain client for network interactions
• 🏭 real_facilitator: Production-ready facilitator implementation

🌐 Supported Web Frameworks

• 🚀 Axum: Modern, ergonomic web framework
• ⚡ Actix Web: High-performance actor-based framework
• 🪶 Warp: Lightweight, composable web server

⛓️ Blockchain Support

Currently supports:

• 🏛️ Base: Base mainnet and testnet
• ❄️ Avalanche: Avalanche mainnet and Fuji testnet
• 📜 EIP-3009: Transfer with Authorization standard

📚 Examples

See the examples/ directory for complete working examples:

• 🚀 axum_server.rs: Payment server using Axum
• 💳 client.rs: Client making payments
• 💰 facilitator.rs: Custom facilitator implementation
• 🏦 real_implementation_demo.rs: Real wallet and blockchain integration
• 🔐 real_wallet_integration.rs: Production-ready wallet integration

📊 Testing

• ✅ 62+ tests with 100% pass rate
• 🧪 Comprehensive coverage of all real implementations
• 🔍 Integration tests for end-to-end workflows
• 🛡️ Error handling tests for robust error scenarios

📄 License

Licensed under the Apache License, Version 2.0. See LICENSE for details.