Ampersend SDK

Multi-language SDK for building applications with x402 payment capabilities. Supports both buyer (client) and seller (server) roles with flexible payment verification and authorization patterns.

Looking for examples? See the ampersend-examples repository.

📦 Language Support

• Python - A2A protocol integration with wallet implementations and payment middleware

  • Python SDK Documentation
  • LangChain Integration

• TypeScript - MCP protocol integration with client, proxy, and server implementations

  • TypeScript SDK Documentation

🤖 Teach Your Agent To Use Ampersend

If you just want your coding agent (Claude Code, Cursor, Codex, etc.) to be able to pay for things online, install the ampersend skill:

npx skills add edgeandnode/ampersend-sdk

This uses the skills CLI to install the skill into your agent's skills directory. The skill handles setup, payment, and configuration — your agent will know what to do when it sees a 402 response or you ask it to call a paid endpoint.

🚀 Quick Start

Python

# Install Python 3.13
uv python install 3.13

# Install dependencies
uv sync --frozen --all-packages --group dev

→ Full Python documentation

TypeScript

# Install dependencies
pnpm install
pnpm build

# Configure environment
cp .env.example .env
# Edit .env with your credentials

# Run MCP proxy server
pnpm --filter ampersend-sdk proxy:dev

# Or run FastMCP example server
pnpm --filter fastmcp-x402-server dev

→ Full TypeScript documentation

📚 Documentation

Core Concepts

x402 Protocol - Transport-agnostic payment protocol for agent and LLM applications that enables pay-per-request patterns. See x402 specification.

Supported Transports:

• A2A (Agent-to-Agent) - Transport protocol for agent communication with payment capabilities
• MCP (Model Context Protocol) - Transport protocol for LLM-tool integration with payment capabilities
• HTTP - Standard HTTP client with x402 payment capabilities (TypeScript)

Key Components:

• Treasurer - Authorizes and tracks payments
• Wallet - Creates and signs payment proofs (EOA and Smart Account support)
• Client - Initiates requests with payment handling
• Server - Verifies payments and processes requests

Repository Structure

ampersend-sdk/
├── python/
│   ├── ampersend-sdk/           # Python SDK package
│   └── langchain-ampersend/     # LangChain integration
└── typescript/
    └── packages/
        └── ampersend-sdk/       # TypeScript SDK package

🔧 Prerequisites

Python

• uv - Dependency management (install)
• Python 3.13+

TypeScript

• Node.js 18+
• pnpm - Package manager

Development

• Test USDC - For payment testing (Circle faucet)
• Private Key - Ethereum wallet for signing payments

📄 License

Apache 2.0 - See LICENSE