x402 is an open payment protocol built on the HTTP 402 Payment Required status code: a server quotes machine-readable payment terms in its 402 response, the client (typically an AI agent) pays in USDC and retries with a payment header, and the content or API result is returned in the same HTTP exchange. It removes accounts, subscriptions and API keys from machine-to-machine commerce.
Market402 is the verified index of the x402 economy: it probes every listed x402 service with real HTTP requests (14,843 endpoints across 1,034 operators at last census), buys from qualifying operators with real USDC, and scores what it observes under published rules. Nothing is self-reported.
The 402 Score is a 0-100 measure of an x402 service computed from real probes: availability, latency, x402 spec compliance, price integrity and paid delivery. The scoring rules are public at /methodology, every score links to its operator page, and scores are never sold or self-reported.
402 Verified means the operator's service was probed with real requests over time, passed spec and reliability checks, and a recent real purchase delivered a valid result. The badge expires if verification lapses - the badge image literally 404s - and it is earned by measurement, never bought.
Market402's latest full census counted 14,843 endpoints from 1,034 operators, of which 6,633 (44.7%) return a spec-compliant 402 challenge. The census runs weekly; monthly aggregates are published at /reports.
Listing is free and instant to request: POST /submit with your endpoint URL. You get immediate spec feedback, your service is probed in the next round, and you can test your 402 response first with the free /selftest.
Yes - all published data (index, scores, reports, score history window) is licensed CC BY 4.0: copy it, build on it, use it commercially, with attribution to Market402 (market402.com). Verification claims are only valid served live from market402.com.
Because both can be gamed: uptime claims are free to make, and on-chain volume can be self-dealt. A probe that pays real USDC and checks whether the service actually delivers cannot be faked by the seller - which is the point of a verified index.