Walinox

Pay in USDT without signal.

Self-custody USDT for kiosks, markets, and everyday LATAM use: the buyer signs offline; the seller settles on-chain and moves the funds the user authorized. That signature travels through the phone’s own capabilities (Bluetooth, QR, NFC, Sound, JSON via SMS).

The problem

In high-inflation, low-connectivity places, cash is heavy, banks are slow or out of reach, and most crypto wallets assume always-on internet. Stablecoins exist, but not for the counter when the customer has no data.

What I built

A PWA on Tether WDK: local non-custodial wallet (seed on device, PIN), optional RainbowKit for extension wallets, and Permit2 settlement in USDT on Ethereum.

• P2P — send, receive, request, pay
• Store / POS — seller manages a product catalog (add, edit, price in USDT or local currency), builds a basket at the counter, charges, and collects offline
• Offline channels — QR, copy, file, NFC, Bluetooth, sound, and light
• QVAC — “in one phrase” helper that fills forms (send, contacts, products) from short natural language
• Extras — MoonPay top-up, contacts, activity, push, biometrics, optional cloud snapshot of app data (never the seed)

How it works

1. Buyer signs an EIP-712 Permit2 permission (no internet required).
2. Signature moves phone-to-phone via QR, copy, file, NFC, Bluetooth, sound, or light.
3. Whoever has network runs permitTransferFrom. Only then does USDT move.

USDT mainnet has no ERC-2612 permit(), so Permit2 is the path. Signing is authorization, not a transfer. Gas online can be paid in USDT via WDK’s 7702 gasless module when available.

Why it matters

This is inclusion infrastructure: spendable digital dollars for people and small shops that banks and always-online wallets leave out, built with WDK so the keys stay with the user.