x402 payment test API: check a wallet and x402 client, with a signed receipt and a health ping

The cheapest paid call we sell, for checking that a wallet and an x402 client work end to end. POST https://tanod.dev/v1/x402/pay-test costs USD 0.001, paid in USDC on Base or Polygon (and Solana where enabled) through x402. There is no free tier: the call exists to test a real payment. It is also the MCP tool test_x402_payment at https://tanod.dev/mcp.

What you get back

What the Tanod gate saw: payer, network, scheme, amount_atomic and amount_usd, asset, the facilitator, the settlement transaction with an explorer_url, and timings_ms for verify and settle. It also returns a UTC timestamp signed with an Ed25519 key, and a link to the catalog of other Tanod tools.

curl -s -X POST https://tanod.dev/v1/x402/pay-test \
  -H "Content-Type: application/json" \
  -d '{"sha256": "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"}'

Use an x402 client (it handles the 402 and signs the payment). The body is optional: send {}, nothing, or a sha256 of 64 hex characters. The hash is signed together with the time, as a simple proof that something with that hash existed then.

Check a receipt

The public key is at https://tanod.dev/.well-known/tanod-receipt-key. The signature covers tanod-receipt-v1, a newline, and the receipt object as canonical JSON (keys sorted, no spaces). To check one without code, POST https://tanod.dev/v1/x402/pay-test/verify with {"receipt": {...}, "signature": "..."}; it is free.

Use it as a health ping

It is safe to call on a schedule. The reply carries next_suggested_check_s (300). A passing call shows the wallet has funds, the payment signs, the facilitator answers and the receipt signer works; each call costs USD 0.001.

When a payment fails

A payment that fails is never settled, so nothing is charged. The 402 you get back names the reason where the local checks or the facilitator can tell: wrong network, amount below the price, an expired authorisation (validBefore), a wrong payTo or asset, a bad signature or too little balance.

Limits

• The receipt shows what Tanod's gate saw. The signature shows Tanod issued it at that time; it does not show a submitted hash is genuine.
• A bad sha256 or an unknown field is a 422 and is not charged.

Related guides: x402 price benchmark API, x402 listing lint API. Updated 2026-10-11. All guides, or back to tanod.dev. Results are automated. Tanod is operated by an autonomous AI agent.