YourAITools

Free x402 endpoint checker

Paste the URL of a paid x402 route. We request it without paying (no payment header is ever sent) and grade the 402 response: does it ask for payment correctly, which x402 versions and networks it supports, and what it costs. Free, no wallet, no signup.

Runs only when you press Check (about 10 checks a minute per network). Results are kept for 60 seconds in this tab, so re-checking the same URL right away shows the saved result.

A point-in-time technical check, not an endorsement. It is an automated, unpaid probe: a good grade doesn’t guarantee that payments settle or that any directory lists you, and it says nothing about data quality, uptime, security or the business behind the URL. It never changes rankings on YourAITools. Fixes from the paid tiers are suggestions to check against the x402 spec. Agents can call the same free check directly: GET https://api.youraitools.co/x402fix/v1/preview?url=…

Read the payment terms from a 402 response

Already have the raw response? Paste the 402 JSON body (x402 v1 or v2) or the base64 PAYMENT-REQUIRED header value to see the x402 version, scheme, network, asset, amount in USDC, payTo, resource and description.

Runs entirely in your browser. Nothing you paste is sent anywhere. Get the raw response with curl -i https://your-endpoint.

Is this your endpoint?

Get it in front of people and agents looking for paid x402 APIs. Listing is free and reviewed for legitimacy and fit. Featured adds a labeled slot at the top of its category for 30 days.

List it freeGet Featured ($29)

Stuck on a fix? Ask in the YourAITools Community (builders getting paid in crypto, x402 help and launches).

Questions

What does the free x402 endpoint checker do?
It sends one unpaid request to the https URL you paste (no payment header is ever sent) and reports whether it answers with a valid x402 402: a grade and score, x402 v1 and v2 support, networks and the price per call. Your browser also tries to read the full payment terms directly: scheme, network, asset, amount in USDC, payTo, resource and description.
Why does it say my browser could not read the 402 directly?
Browsers only let a page read another site’s response when that site allows it with CORS headers. Many x402 servers don’t. The grade still comes from our server-side check; for the full terms, run curl -i on your endpoint and paste the 402 body or the PAYMENT-REQUIRED header into the parser on this page. Allowing CORS and exposing PAYMENT-REQUIRED also helps browser buyers pay you.
Does the checker ever pay or spend money?
No. Both the server-side check and the browser request are unpaid. Nothing is signed and no wallet is needed. The paste parser runs entirely in your browser and sends nothing anywhere.
How is the amount converted to USDC?
x402 amounts are whole numbers in the asset’s smallest unit. When the asset is a known USDC contract or mint (Base, Polygon, Arbitrum One, Ethereum, Optimism, Avalanche, Solana and their common testnets), we divide by 10^6 because USDC has 6 decimals. Any other asset is shown as raw atomic units and not converted.
Is a good grade an endorsement?
No. It is an automated, point-in-time technical check. It does not guarantee that payments settle or that any directory lists you, and it says nothing about data quality, uptime, security or the business behind the URL. It never changes rankings on YourAITools.
My endpoint passes. How do I get it in front of buyers?
List it on YourAITools for free (reviewed for legitimacy and fit, usually live within 3 to 5 days), or get Featured for $29 for 30 days, payable by card or in USDC. Paying never guarantees approval and is refunded if the listing is rejected.

Verified (paid) endpoint check

Coming soon. Not on sale yet.

The end-to-end check makes a real paid call to your API. It starts once our test wallet is set up and funded. Until then we don’t take payment for it. Please don’t send USDC for it. Want to know when it opens? Email us.

What it will test

  1. An unpaid request returns HTTP 402 with valid x402 payment requirements (price, network, asset, pay-to).
  2. The requirements match what your listing says (network, token, price).
  3. A real test payment from our wallet is accepted and settles on-chain.
  4. The paid request returns a successful response (2xx) with a payment-response header.

Planned terms

  • Planned price: $19 USDC, one-off, payable on Base or Solana. The price is confirmed when the check opens.
  • A written report with the request, the 402 response, the settlement transaction and the result.
  • Pass: an “Endpoint checked on YYYY-MM-DD” note on your listing. Fail: the report, plus one free re-test within 30 days.
  • A point-in-time technical check, not an endorsement. It says nothing about data quality, uptime, security or your business, and it never changes rankings.

New to x402? Read what is x402. Want your tool listed? Submit it free.