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Description

ChainPe: Payment and Reputation for AI Agents

ChainPe is open-source infrastructure that lets AI agents and other software pay each other and check each other's reputation, with no human involved. It runs on Arbitrum and uses two open standards: x402 for pay-per-request USDC payments and ERC-8004 for on-chain identity and reputation.

The Problem

AI agents now call APIs, buy data and hire other agents, but payments still assume a human is doing the setup:

- Agents can't pay on their own. Paid APIs need an API key, an account and a prepaid balance, all set up by a person ahead of time.

- Charging per call is hard for providers. It means building billing, metering and a payments backend.

- Agents can't tell who to trust. There's no portable, verifiable way to judge whether a service or agent is reliable.

The Solution

For API providers: one command (chainpe start) puts an x402 payment proxy in front of any HTTP API. Unpaid requests get a 402 Payment Required offer, a facilitator checks and settles each payment in USDC, and the request is passed on to the provider's backend. The backend doesn't change and never handles keys or payment logic.

For agents: cp.fetch() works like the standard fetch. When it gets a 402, it signs a gasless USDC authorization (EIP-3009) and retries. Agents only need to hold USDC. Facilitators (Coinbase CDP and PayAI, with automatic failover) pay the gas on Arbitrum.

Reputation: agents leave feedback on the canonical ERC-8004 registries, and a review only counts if it comes with proof of a real payment. That makes reputation hard to fake, and other agents can check it.

Spending limits: the PolicyVault contract sets budgets on-chain, so the chain itself rejects any payment over the limit rather than relying on a backend.

Discovery: one search covers the ChainPe registry, Coinbase's x402 Bazaar and ERC-8004 agents, with results ranked by reputation backed by payments.

ChainPe Whitepaper : https://drive.google.com/file/d/1Ek62vIrT-XiNoqcIc4-SoRdpEvUJPy7j/view?usp=drivesdk

What We Built

- @chainpe/sdk: the core SDK for payments, discovery, reputation and PolicyVault

- @chainpe/ai-tools: ready-made tools for the Vercel AI SDK and LangChain

- @chainpe/cli: the provider proxy, plus fetch and discover commands for consumers

- @chainpe/agent: an LLM agent that finds and pays for services on its own

- ChainPe Wallet (MCP): a USDC wallet for Claude Desktop

- Marketplace dashboard and indexer: browse services, payments and reputation

- Self-hostable facilitator: settles payments with no third-party dependency

- Smart contracts: ChainPeRegistry (UUPS upgradeable) and PolicyVault

Why Arbitrum

Payments of a cent or less only make sense when fees are tiny and blocks are fast. Arbitrum's roughly 250 ms blocks, low fees, native USDC and canonical ERC-8004 deployments let agents pay per request at the speed they work.

Vision

ChainPe is meant to be the base layer for agents doing business with each other: any API can be priced per request, any agent can pay without help, and every review is backed by a real payment.

GTM Plan : https://drive.google.com/file/d/1mPY_6lAtQf3YNq1lDgn-mlbC_D_oeYLd/view

Progress During Hackathon

During the buildathon, we moved ChainPe to Arbitrum and built out the complete payment + reputation stack end to end. We deployed ChainPeRegistry and PolicyVault on Arbitrum Sepolia as UUPS-upgradeable contracts, with Hardhat test coverage including a mainnet-fork E2E test. For reputation, we went with the canonical ERC-8004 identity and reputation registries on Arbitrum rather than building another custom version. On the payments side, ChainPe now supports x402 v2 with gasless USDC payments through EIP-3009. Payments are settled through Coinbase CDP and PayAI with automatic failover, alongside our own self-hostable facilitator. We also proved the entire flow on-chain: registered a provider as ERC-8004 agent #249, listed a paid API for 0.01 USDC, completed an SDK call settled by PayAI, and submitted a review with payment proof that our indexer verified. Every step is backed by an on-chain Arbiscan transaction. Around the protocol, we shipped the ChainPe SDK, CLI, AI tools for Vercel AI and LangChain, agent tooling, a Claude Desktop MCP wallet, our Postgres + REST indexer, and a Next.js marketplace dashboard. For discovery, we brought everything into one search layer across the ChainPe registry, Coinbase’s x402 Bazaar, and ERC-8004 agents. And this is more than just a buildathon prototype. We’ve already put together a GTM strategy focused on Arbitrum data/API providers and published the ChainPe whitepaper. The goal is simple: make APIs and agent services programmable, discoverable, payable, and reputation-aware onchain.

Fundraising Status

Bootstrapped. We haven't raised outside funding yet. We're applying for an Arbitrum grant to fund a $10,000 USDC credit pool that will bring the first 200 agent teams onto paid mainnet calls. We're open to conversations with investors and ecosystem partners after mainnet launch.