AI × Web3
Agent Pay
An AI agent with a wallet. It finds a tool, checks the price, pays, and gets the data — without asking you.
The Problem
AI agents are becoming capable of doing real work. But the moment they need paid data — weather APIs, stock prices, detailed search — they stop. They can't pay. They don't have wallets. They can't negotiate.
So a human has to step in, enter a credit card, manage API keys, and pick a subscription tier. The autonomy breaks down exactly when it gets interesting. The existing payment infrastructure wasn't built for machines. It was built for humans with browsers and bank accounts.
What Was Built
AgentPay is an autonomous AI agent that can discover paid tools in a marketplace, negotiate access, pay for them in real-time using cryptocurrency, and retry the original request — without any human in the loop.
The core is the HTTP 402 payment loop: the agent (Groq LLaMA-3) makes a request, the server responds 402 Payment Required with a price and wallet address, the agent catches it and pays autonomously via Yellow Network state channels (instant, off-chain, no gas fees), then retries with cryptographic payment proof in the header.
If Yellow Network's state channel isn't available, the system falls back automatically to a standard on-chain EVM transaction. The agent never gets stuck. The Yellow Network SDK is wired in for real — not mocked — with real USDC balance fetching, token approvals, and off-chain settlement.
- →HTTP 402 payment loop — request → server challenge → autonomous payment → retry with proof
- →Yellow Network SDK (@erc7824/nitrolite v0.5.3) — real off-chain state channel payments
- →Automatic EVM fallback when state channel is unavailable
- →Groq LLaMA-3 as the agent brain — tool selection and context management
- →x-402-payment header with cryptographic payment proof for server verification
- →React + Vite frontend, Node.js/Express backend acting as the paid tool marketplace
Outcomes
- →Full 402 payment loop working end-to-end — not mocked or simulated
- →Real Yellow Network SDK integration verified: balance fetch, approve, pay, signature
- →On-chain EVM fallback ensures the agent never hits a dead end
- →Demonstrates the core primitive for agentic commerce — machines paying machines
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