This monorepo contains Python SDKs for the x402 payment protocol - enabling instant micropayments for both API providers and AI agents.

Lightning-fast x402 payment integration for FastAPI and modern Python web frameworks. Accept micropayments with just 3 lines of code!

from fastapi import FastAPI
from fast_x402 import x402_middleware

app = FastAPI()
app.add_middleware(x402_middleware, 
    wallet_address="0xYourAddress",
    routes={"/api/premium": "0.10"}
)

Enable your LangChain AI agents to make autonomous micropayments. Give your agents economic agency!

from x402_langchain import create_x402_agent

agent = create_x402_agent(
    private_key="0xYourPrivateKey",
    llm=ChatOpenAI(model="gpt-4"),
    spending_limit_daily=10.0,
)

• Zero Protocol Fees - Only pay ~$0.001 in blockchain gas
• Instant Settlement - 2-second finality on Base L2
• Simple Integration - Add payments in minutes, not weeks
• Built for AI - Native support for autonomous agent payments
• Secure by Design - EIP-712 signatures, spending limits, domain restrictions

# For API providers
pip install fast-x402

# For AI developers  
pip install x402-langchain

# Clone the repository
git clone https://github.com/x402/x402-sdk.git
cd x402-sdk

# Install dependencies
pip install poetry
poetry install

# Run tests
poetry run pytest

# Run examples
cd packages/fast-x402/examples
python basic_api.py

• fast-x402 Documentation - For API providers
• x402-langchain Documentation - For AI developers
• Protocol Specification - Technical details

• Monetize APIs with micropayments
• Replace complex subscriptions with pay-per-use
• Accept payments from AI agents automatically
• Zero payment processing fees

• Build agents that can purchase data autonomously
• Access premium APIs without manual API keys
• Implement spending controls and limits
• Track agent expenditures and ROI

The x402 protocol enables instant payments through HTTP headers:

1. Client requests resource → GET /api/data
2. Server returns 402 → Payment details in response
3. Client signs payment → EIP-712 standard
4. Client retries with payment → X-Payment header
5. Server delivers resource → Instant settlement

• EIP-712 Signatures - Cryptographically secure payments
• Replay Protection - Each payment has unique nonce
• Spending Limits - Control agent expenditures
• Domain Restrictions - Whitelist/blacklist payment destinations

We welcome contributions! Please see our Contributing Guide for details.

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Submit a pull request

• JavaScript/TypeScript SDKs
• Rust implementation
• Multi-chain support (Polygon, Arbitrum)
• Advanced payment schemes ("upto", "subscription")
• Payment analytics dashboard
• Agent marketplace integration

This project is licensed under the MIT License - see the LICENSE file for details.

Built on top of the x402 protocol by Coinbase. Special thanks to:

• The Coinbase team for creating the x402 standard
• The Anthropic team for the Model Context Protocol
• The LangChain community for the agent framework

• 💬 Discord Community
• 📧 Email Support
• 🐛 Issue Tracker
• 🐦 Twitter Updates

Built with ❤️ by the x402 community

Website • Documentation • GitHub