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What is Crossmint Agentic Finance?

Crossmint Agentic Finance provides reference implementations for AI agents to make autonomous blockchain payments. These examples demonstrate how agents can pay each other for services, access paywalled APIs, and conduct peer-to-peer transactions using USDC on EVM and Solana chains.

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Key Features

x402 Payment Protocol

HTTP paywalls using the 402 Payment Required status code for seamless payment integration

Agent-to-Agent Payments

Autonomous agents communicating and transacting with each other using the A2A protocol

Crossmint Smart Wallets

Gasless, programmable wallets with built-in USDC support for simplified payment flows

Multi-Chain Support

Works on Base Sepolia testnet and Solana Devnet with production-ready patterns

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Use Cases

These reference implementations cover three primary scenarios:

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HTTP Paywalls (x402)

Minimal servers requiring USDC payment to access endpoints. Perfect for:
  • Paid API services
  • Premium content delivery
  • Metered usage billing
Start with: ping demo for pure backend or ping-crossmint for full-stack

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Agent-to-Agent Payments (A2A)

Autonomous agents paying each other for services and tool access:
  • AI agents purchasing capabilities from other agents
  • Automated service marketplaces
  • Tool access with payment verification
Start with: hello-eoa-a2a for basics or events-concierge for production patterns

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Production Examples

Real-world implementations with advanced features:
  • XMTP chat-based commerce
  • Autonomous ad bidding systems
  • Calendar booking with payments

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Get Started

Quick Start

Run your first x402 paywall in under 5 minutes

Prerequisites

Set up your development environment and get testnet tokens

Core Concepts

Understand the x402 protocol and payment flows

HTTP Paywalls

Build your first payment-protected API endpoint
All examples use testnet tokens (Base Sepolia or Solana Devnet) and are safe to experiment with. Get free testnet USDC from the Circle faucet.

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Architecture Overview

The reference implementations demonstrate:
  • Payment Middleware: Express and Hono middleware for automatic payment verification
  • Client Libraries: Axios and Fetch adapters for x402 payment headers
  • Smart Wallets: Crossmint SDK integration for gasless transactions
  • Signature Standards: EIP-712 signatures and ERC-6492 validation
  • Production Patterns: Cloudflare Workers, Durable Objects, and MCP integration

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Community & Support

GitHub Repository

View source code and contribute

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