x402 catalogs are noisy. Endpoints drop off and the listing stays. 402Signal is not a catalog. It is a live-endpoint router.
An unpaid call to POST /route returns HTTP 402. Pay $0.01 USDC on Base, Solana, or Algorand. We verify, probe, then settle. If the target answers, we return its URL plus the health snapshot from that probe: last probe time, latency_ms, and whether it presented a 402 challenge. If nothing is live we fail closed — HTTP 503, live: false — and you still pay $0.01 for the probe report. Same price for a live URL or an honest miss.
$0.01 per route. GET /health is free liveness {"ok":true} — not a paid listing. The probe snapshot is on /route.
POST /route
Body. url is optional. If omitted we fuzzy-match Coinbase discovery, probe up to five, return the first live endpoint. The preview below is the actual JSON we POST — it updates as you type.
Live response (health snapshot baked in):
{
"live": true,
"url": "https://example.com/x402/balance",
"status": 402,
"latency_ms": 87,
"has_402_challenge": true,
"probed_at": "2026-08-29T22:00:00-04:00",
"tried": 1,
"health": {
"live": true,
"last_probe": "2026-08-29T22:00:00-04:00",
"latency_ms": 87,
"has_402_challenge": true,
"status": 402
}
}