Every x402 listing on the Bazaar,
checked daily. Publicly.
Check any x402 endpoint now
Paste a URL. We fetch it, parse the 402 PAYMENT-REQUIRED header, and show you what your buyers actually see. No USDC sent. Own the endpoint? Claim it right after.
Your listing breaks silently. Don't let it break your sales.
Every x402 seller eventually ships a bad config: a redeploy moves the payout wallet, a price change never reaches the catalog, a host dies on a Friday. Buyers don't email you about it — they just pay someone else. Watch402 watches your listing the way buyers do, around the clock, and messages you in Telegram the moment anything changes.
$5 USDC per listing for 30 days of alerts, paid on Base — a plain USDC transfer, or natively over x402 if you're an agent (POST /v1/x402/alerts, EIP-3009, settled via facilitator). Monitoring and public status pages are free forever, for every listing in both catalogs.
1 · Claim free
Open your status page and sign one message with the listing's own payout wallet. Proof of ownership without accounts, email or card.
2 · Arm Telegram
Tap the link after claiming and press START — @watchx402_bot links itself to your listing automatically.
3 · Get alerted
Daily rechecks diff price, wallet and network against the catalog. Drift, downtime or recovery → Telegram DM within hours.
Continuous drift detection
Live PAYMENT-REQUIRED challenges diffed daily against advertised terms: price, payout wallet, network, scheme, HTTP method.
Downtime & recovery alerts
Dead endpoints and recoveries are caught by the same probes that power the public stats — no separate ping service needed.
A public status page per listing
Every monitored endpoint gets /s/{id}: current verdict, price, wallet, network and last check time. Shareable proof you're alive.
Agent-native checkout
The alert subscription is itself an x402 resource — agents discover it in the bazaars and subscribe with a signed USDC payment. No keys, no accounts.
Check before you buy
Integrating someone's x402 API? Run it through the demo above first — real verdict, price, wallet and network in seconds, no account needed.
Coverage that refreshes weekly
New PayAI Bazaar and Coinbase CDP listings are ingested every Sunday at 00:00 UTC. You never register anywhere.
Watch402 watches the two x402 discovery catalogs — the PayAI Network Bazaar and Coinbase CDP x402 Discovery — covering 40,937 paid-API endpoints. Each listing is rechecked on a schedule matched to its health: anything serving payments is verified every day, dead endpoints are swept weekly. We hit your endpoint, parse the live HTTP 402 PAYMENT-REQUIRED challenge, and compare price, payout wallet and network against what the catalog advertises. When they stop matching, it shows up here.
PayAI Network Bazaar
The largest x402 discovery catalog, at facilitator.payai.network/discovery/resources. Watch402 ingests every listing — resource URL, advertised price in USDC atomic units, payout wallet, network and scheme — and re-probes each endpoint daily with the HTTP method and example inputs the listing declares.
Coinbase CDP x402 Discovery
Coinbase's official catalog via the Developer Platform, at api.cdp.coinbase.com/platform/v2/x402/discovery/resources. ~15,000 additional listings, many not present in any other index. Same daily treatment: live 402 fetch, header parse, full diff against the advertised terms.
What a daily check covers
We request the exact resource URL with its declared method (GET/POST), example path and query parameters, and example body. We parse the base64 PAYMENT-REQUIRED header from the 402 response, extract every accepts[] entry, and diff price, payTo wallet, network and scheme against the catalog. Verdicts: live · drifted · broken · misconfigured · unreachable.
Seller-side, not buyer-side
Every other x402 trust tool warns the buyer before they pay. We watch from your side of the table: what your PayAI or Coinbase listing looks like right now, and whether it matches what the catalog promises.
Detects the #1 break mode
Price drift. ScoutScore's February 2026 audit found 58% of Bazaar listings advertise the wrong price. Every endpoint here is rechecked daily and diffed against its advertised terms.
Zero setup, free monitoring
No signup, no API key, no card. Paste any Bazaar URL above and see exactly what buyers see. Monitoring is free for every listing; Telegram alerts are $5 USDC per 30 days.
The pitch, in three sentences
If you sell on x402, you have a listing in a discovery catalog — the PayAI Network Bazaar, Coinbase CDP x402 Discovery, or both. That listing can break in dozens of ways: your wallet changes, your price drifts, your server dies, your resource URL 404s. The protocol won't tell you. Your buyers won't tell you. They'll just stop paying.
Watch402 is the thing that tells you. We recheck every listing daily, parse the live 402 challenge, and diff it against what the Bazaar advertises — price, wallet, network, scheme. Everything we find is public on this page, free.
The demo above works on your endpoint right now. No signup — paste a URL and see what buyers see. Claim your listing to arm Telegram alerts; agents can subscribe programmatically at POST /v1/x402/alerts. Everything runs live today.
Frequently asked
What does Watch402 cost?
Monitoring, public status pages and the read API are free for every listing in both catalogs. Telegram alerts are $5 USDC per listing per 30 days, paid on Base.
How do I get alerts for my listing?
Claim the listing free by signing with its payout wallet from your status page (/s/{id}), press START on @watchx402_bot, then pay $5 — by USDC transfer or native x402 payment.
What triggers an alert?
Your listing going unreachable, coming back, or drifting from its advertised terms: price changed, payout wallet swapped, network or scheme changed. Each DM includes what changed and when.
How fresh is the data?
Listings that serve payments are rechecked at least every 24 hours; dead or unreachable ones weekly; new and claimed listings immediately. Every page shows its last check time.
Can AI agents subscribe to alerts?
Yes — /v1/x402/alerts is a native x402 resource: agents fetch it, receive the 402 challenge, and pay $5 USDC on Base with one EIP-3009 signature. No accounts anywhere in the flow.
Does Watch402 ever spend my funds?
No. Probes stop at the unpaid 402 response. Alert payments move only the $5 you authorize, from your own wallet, settled through a public facilitator.