AgentPay AI — Backend API

Express.js API gateway for the AgentPay AI platform — AI inference gated by on-chain USDT payments on BotChain.

Live API: https://agentpay-backend-eight.vercel.app
Frontend: https://agentpayfrontend.vercel.app
GitHub Org: https://github.com/agentpay-ai

---

What it does

The backend is an Express.js server deployed on Vercel that:

• Accepts AI requests (chat, image, code) and gates them behind on-chain USDT payment verification
• Supports three payment methods:
  • Per-request — user submits a X-AgentPay-Payment-Tx header with a real on-chain USDT transfer tx hash
  • Prepaid session — user deposits USDT once, receives a signed session token, uses it for multiple requests
  • x402 — standard HTTP 402 payment-required challenge/response flow
• Proxies Claude (Anthropic) AI completions
• Manages agent reputation via ERC-8004 on BotChain
• Relays BotChain transactions

---

API Endpoints

Method	Path	Description
GET	/health	Status, model info, payment config
POST	/api/chat	Claude chat completion (payment-gated)
POST	/api/image	Image generation (payment-gated)
POST	/api/code	Code generation (payment-gated)
GET	/api/reputation/:address	Agent reputation lookup
POST	/api/attribution	Attribute a request to an agent
POST	/api/credits/deposit	Verify on-chain USDT deposit → issue session token
POST	/api/botchain/relay	Relay a signed BotChain transaction

---

Tech Stack

• Runtime: Node.js + Express.js
• AI: Anthropic Claude (claude-opus-5) via @anthropic-ai/sdk
• Payments: @x402/express middleware + direct USDT transfer verification
• Chain: BotChain (EVM-compatible, chain IDs 968 / 677)
• Deployment: Vercel (serverless)

---

Local Development

git clone https://github.com/agentpay-ai/agentpay_backend
cd agentpay_backend
npm install
cp .env.example .env   # fill in your keys
npm run dev            # starts on http://localhost:3001

Environment Variables

Variable	Description
ANTHROPIC_API_KEY	Anthropic API key
ANTHROPIC_MODEL	Model override (default: claude-opus-5)
ANTHROPIC_BASE_URL	Override AI base URL (default: https://api.anthropic.com)
X402_NETWORK	testnet or mainnet
X402_API_KEY	x402 facilitator API key
PAYMENT_RECIPIENT_ADDRESS	Vault address that receives USDT
BOTCHAIN_RPC_URL	BotChain RPC endpoint
SESSION_SECRET	HMAC secret for prepaid session tokens

---

Related

• Frontend repo: agentpay-ai/agentpay_frontend
• Live site: https://agentpayfrontend.vercel.app