kevin2003050666-coder/x402-micro-tollgate

**Visa for AI agents that can’t hold a card.**
Second-scale settlement bridge for agent traffic — the Web3 tollbooth that clears USDC micropayments and takes **0.1%**.
> 为千万级无支付能力的 AI Agent 提供秒级过桥清算，抽成 0.1% 的 Web3 版 Visa 收费站
**Security backed by Coinbase CDP.** We don't touch your keys or settle payments on custom cryptography — EIP-3009 authorization nonces are single-use at the CDP facilitator (source of truth for on-chain uniqueness). The gateway hardens four buyer/seller trust surfaces: **payment-proof replay/race**, **SSRF on URL fetch**, **upstream bypass (shared-secret trust header)**, and **Base congestion / settle-latency** (pending + retry same proof — never treat HTTP timeout alone as “payment failed”).
What it is
A thin self-hosted tollgate in front of your API or MCP tools. When an agent calls a paid route, it gets **HTTP 402 as a price tag** (not a hard deny). It pays a small USDC (or configured USDT) amount; you deliver. Default clearing is **Base + USDC** via **Coinbase CDP**; multi-network accepts are env-driven (see matrix below). Humans can still hit a free path; agents convert at the booth.
Self-host is free (MIT). Repo: github.com/kevin2003050666-coder/x402-micro-tollgate · Questions: 2767111713@qq.com
> Not an official Coinbase product. Not a full agent marketplace. Not a billing SaaS. A sharp Visa-style tollbooth. Not fiat custody.
> Why this exists: MANIFESTO.md — pain, engineering, on-chain proof, MIT.
Network × asset matrix
Default deploy profile: **Base USDC only** (dev: Base Sepolia). Enable multi with NETWORKS + ASSETS or ACCEPTS_JSON / X402_* aliases. Browser HTML 402 shows a **chain + asset picker** when more than one accept is configured.
| Network | CAIP-2 | USDC | USDT | Status | Facilitator / notes |
|---|---|---|---|---|---|
| Base | eip155:8453 | native Circle | bridged | **live** | CDP exact. FeeSplitterFactory **live** (deployments/base.json) |
| Base Sepolia | eip155:84532 | test USDC | — | **live** | CDP testnet |
| Optimism | eip155:10 | native | bridged | config-ready | Addresses wired; **not** on current CDP matrix |
| Arbitrum One | eip155:42161 | native | bridged | **live** | CDP exact; factory stub |
| Polygon PoS | eip155:137 | native (not USDC.e) | PoS USDT | **live** | CDP exact; factory stub |
| BNB Smart Chain | eip155:56 | peg 18 dec | peg 18 dec | config-ready | Not on CDP list |
| Ethereum | eip155:1 | native | Tether | config-ready | Facilitator-dependent |
| Avalanche C-Chain | eip155:43114 | native | USDT | config-ready | In @x402/evm defaults |
| Celo / Sei | eip155:42220 / 1329 | USDC | — | config-ready | Catalog extras |
| Solana | solana:5eykt… | SPL USDC | SPL USDT | **experimental** | CDP lists Solana; gateway stubs + optional SVM paywall (SOLANA_PAY_TO) |
| TRON | tron:mainnet | — | TRC-20 | **planned** | No scheme in deps — **never** in accepts[] |
USDT on EVM typically uses extra.assetTransferMethod: "permit2" (not EIP-3009). FeeSplitter production path remains **Base + USDC**; other chains are config stubs under contracts/deployments/.
Browser wallets
| Wallet | Role |
|---|---|
| Coinbase Smart Wallet (Passkey) | Primary CTA |
| MetaMask | Via wagmi injected target |
| Injected | Other browser wallets |
| WalletConnect | When WALLETCONNECT_PROJECT_ID set |
| Solana paywall | Experimental, behind Solana accepts / PAYWALL_SVM |
| TronLink | **Not offered** (TRON planned only) |
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Who it’s for
- **API sellers** who want agents to pay per call — without building a billing console or selling monthly seats
- **Tool builders** shipping paid MCP endpoints into Cursor / Claude
- **Operators** who want Visa-like take-rate economics (**0.1%**), not hosting invoices
How money works
1. **Price tag** — unpaid traffic gets HTTP 402 with the amount due (conversion, not rejection)
2. **Pay** — the agent settles a USDC micropayment in seconds via Coinbase CDP
3. **Unlock** — the tollgate proxies to your upstream; you keep ~**99.9%**, protocol take **0.1%**
No protocol monthly fee. Monetization is the toll — like interchange on card rails.
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1-minute quickstart
Requires Node.js 22+.
**npx one-liners** (no clone):
--seller / -s sets X402_PAY_TO before boot (env vars still work). Default without --stdio is HTTP + /mcp on port 8402.
Agent / crawler docs: llms.txt (also GET /llms.txt and GET /.well-known/llms.txt) · OpenAPI 3.1: docs/openapi.yaml · well-known: GET /.well-known/x402.json, GET /.well-known/agent-card.json
Alternative one-liner: docker compose up --build