The QR rail,
on chain.

Quay is a payment terminal that turns Singapore's SGQR rail into an on-chain checkout. A shopper scans the merchant's existing SGQR sticker, picks any token in their wallet, and the merchant receives a stablecoin. The QR doesn't change. The merchant's books don't change. Only the rail behind it does.

We are not a wallet. We are not a DEX. We are the thin layer that makes an existing QR work for crypto-native shoppers and pays out in something a Singapore SME accountant will accept.

Every Quay transaction is three steps, atomic in a single Sui programmable transaction block.

1. 01

   Scan

   Parse the EMVCo TLV payload from the SGQR. Extract the merchant UEN, amount (if present), and currency. Look up the UEN's on-chain merchant record to resolve the payout address and preferred settlement token.

2. 02

   Quote

   Fetch a live SGD price from Pyth. Ask Cetus Aggregator for the best route across every Sui DEX from the shopper's chosen input token to the merchant's settlement token. Show net amount, slippage, and gas before the shopper signs.

3. 03

   Settle

   One PTB: swap input → settlement token via the aggregator route, transfer to merchant, emit an on-chain receipt event. If the swap or transfer fails, the whole transaction reverts. The shopper either pays exactly the agreed amount or pays nothing.

The merchant's phone polls for the receipt event and shows a confirmation. Median end-to-end latency on mainnet is currently under three seconds from sign to confirmation.

• Any liquid Sui token. SUI, USDsui, DEEP, CETUS, and anything Cetus Aggregator can route through.
• No off-ramp. Skip the exchange-withdraw-bank-card loop. Pay the merchant directly.
• No card, no KYC at the till. You sign with your wallet. The merchant sees a receipt, not a card number.
• Non-custodial throughout. Quay never holds your funds. The swap and the transfer happen in one transaction signed by you.
• One tax event. Disposing of crypto to pay a merchant is a single taxable event in most jurisdictions, not the two-step off-ramp-then-pay most users do today.

• Settle in USDsui by default. Switch settlement token any time from the merchant dashboard.
• 90-second onboarding. Sign in with Google via Enoki zkLogin. No seed phrase, no app install, no hardware.
• No PCI scope. You never touch a card number. No acquirer, no chargebacks, no monthly terminal rental.
• Sponsored gas.Payer-side gas is sponsored so shoppers don't need SUI to pay you.
• Idle-balance yield. Optional: route idle USDsui balances into a vetted Sui yield strategy from the merchant dashboard. Toggle off any time.
• GST-ready receipts. Every transaction emits an on-chain event with UEN, SGD-equivalent at Pyth quote time, token settled, and tx digest. Export to CSV for your accountant.

Quay sits on three primitives. Each is replaceable; none is custom-built where a battle-tested option exists.

• Non-custodial.Quay's contracts cannot hold shopper or merchant funds. The settle PTB transfers the output of the swap straight to the merchant in the same call.
• Atomic-or-revert.Swap and transfer share a transaction. A failed route or insufficient liquidity reverts the whole call — the shopper's tokens stay where they were.
• Quoted amount is signed.The shopper signs the exact SGD-equivalent and minimum-out. Front-running or quote drift can't silently change what they pay.
• Merchant directory is on-chain.The UEN → payout-address mapping is a Sui object the merchant controls. Quay can't redirect funds.
• zkLogin keys. Merchant accounts are zkLogin addresses. Recovery is via the underlying OAuth provider; Quay never sees a private key.

Every settled payment emits a PaymentReceipt event with these fields:

{
  merchant_uen: "53123456A",
  payer:        "0x...",
  merchant:     "0x...",
  input_token:  "0x2::sui::SUI",
  input_amount: "1234567890",
  settled_token:"...::usdsui::USDSUI",
  settled_amount:"9_870_000",
  sgd_quote:    "13.42",
  pyth_price_id:"0x...",
  tx_digest:    "...",
  ts_ms:        1731628800000
}

The merchant dashboard reads these events and renders a daily ledger with SGD totals at quote time, settled-token totals, and tx digests for audit. CSV export is one click.

• DuitNow (MY), QRIS (ID), UPI (IN), PIX (BR). Same EMVCo-style payload, different country issuer. Each is a directory + parser, not a rewrite.
• Apple ID and more OAuth providersfor shopper accounts who'd rather not install a wallet at all.
• Merchant payout schedules — auto-sweep into a treasury wallet, an off-ramp partner, or a yield strategy.
• Refunds. Merchant-signed reverse PTB against the original receipt event.