Take any REST API, Postgres function, Airtable base, or custom HTTP service you already run — wrap it with HTTP 402 payment gating using the x402 protocol — and AI agents (or any HTTP client) can pay per-call in USDC without API keys, OAuth, or human account setup. You ship the complete payment layer: x402 middleware + on-chain verifier + replay protection + rate limiter + tests + deploy templates. ## What's included - **x402 middleware** — Express / Fastify / Hono / FastAPI / Next.js / Cloudflare Workers; intercepts requests without payment header → returns 402 with payment instructions - **On-chain payment verifier** — Base (default), Solana, Polygon; verifies USDC transfer to your receiver address, correct amount, correct nonce, within validity window - **Idempotency + replay-protection store** — Postgres or Redis-backed; rejects payment proof reuse; configurable window - **Per-payer rate limiter** — by payer address, by IP, by API key (when present); sliding window - **Receipt generator** — signed receipt per paid call; auditable for revenue accounting + dispute resolution - **Unit + integration tests** — Vitest / Pytest harness; mocked chain client + real-testnet integration mode - **Dockerfile + deploy templates** — Vercel, Cloudflare Workers, AWS Lambda, ClawHQ container, Fly.io - **Price discovery endpoint** — /.well-known/x402 returns price + accepted chains + receiver address per route - **MCP pairing** — natural pair to MCP Server Generator: MCP exposes the interface, x402 exposes the price; agents discover and pay autonomously - **YC RFS Summer 2026 #12 aligned** — agent-to-agent commerce infrastructure ## Limitations - **Not a wallet** — pairs with any USDC-holding wallet (Coinbase Wallet, MetaMask, agent wallets); generates payment instructions, doesn't custody funds - **Not a chain indexer** — uses native RPC for verification; high-throughput services should pair with Alchemy / QuickNode - **Not a fiat gateway** — USDC in, USDC out; off-ramp to USD via Coinbase / Circle is your existing rail - **Not legal counsel** — accepting crypto payments has jurisdictional implications (US MSB, EU MiCA); high-volume operators need counsel - **Stablecoin-USDC-first** — ETH / BTC / other-stablecoin support possible but not the default path ## Best fit API operators monetizing per-call without API key infrastructure: data providers, AI inference endpoints, scraping APIs, niche datasets, agent tools. Especially valuable for solo operators who want to sell API access to AI agents (not humans) — agents have no email, no credit card, no OAuth account, but they have a USDC wallet. x402 makes them first-class customers, and this generator ships the entire payment layer in an afternoon instead of a quarter.
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