Start in 60 seconds.
Create the watch. Let RoundWatch own the wait.

Define the exact payment

Send the expected sender, receiver, atomic amount, and optional invoice note. The watched asset is server-selected MainNet USDC, not a caller-controlled field. The addresses below are valid public example addresses from the verified MainNet proof.

{
  "idempotencyKey": "invoice-2026-09-17-001",
  "expectedSender": "3YFZ47IAKPB4H6B7U6MXI35HCAB5E6DA47UANIHOON53J7I5SMXUSYQXQQ",
  "expectedReceiver": "EQPLN32HPLPGBCNPOZUL6BL34CTNQGT3VAAMNAJWSIZGQ5CUNXOHB634XY",
  "atomicAmount": "1",
  "invoiceNote": "roundwatch:invoice-2026-09-17-001"
}

Inspect the 402 before paying

An ordinary request returns 402 Payment Required. This is a free preflight. No payment is sent until an x402-capable client signs and retries the same request.

curl -i -X POST https://roundwatch-api.onrender.com/v1/watch \
  -H "content-type: application/json" \
  --data '{"idempotencyKey":"invoice-2026-09-17-001","expectedSender":"3YFZ47IAKPB4H6B7U6MXI35HCAB5E6DA47UANIHOON53J7I5SMXUSYQXQQ","expectedReceiver":"EQPLN32HPLPGBCNPOZUL6BL34CTNQGT3VAAMNAJWSIZGQ5CUNXOHB634XY","atomicAmount":"1","invoiceNote":"roundwatch:invoice-2026-09-17-001"}'

Before a paid MainNet retry, verify the advertised network, asset, amount, receiver, and resource URL. The guarded reference client in this repository performs those checks before it can spend.

Settle with an x402-capable client

Wallet signing stays in the client process. RoundWatch does not need your mnemonic or private key. The repository includes a guarded MainNet reference flow using @x402/fetch and@x402/avm.

MainNet spends real USDC. Use TestNet while integrating unless you deliberately intend to pay on MainNet.

Save the watch ID and leave

A successful paid request returns a durable watchId. RoundWatch activates from a safe Algorand round, persists the scan cursor, and owns the waiting obligation after your process exits.

{
  "watchId": "f5d2fb6f-b224-4aae-989c-87a5418fd2ae",
  "message": "The watch is returned only if x402 settlement and durable activation succeed"
}

Read the result later

Poll the public status endpoint whenever your workflow returns. A matched watch exposes the exact Algorand transaction ID and confirmed round that satisfied the watch.

curl -sS https://roundwatch-api.onrender.com/v1/watch/YOUR_WATCH_ID