Finna

The problem

Finna is a crypto-native finance app: hold stablecoins, spend in naira, borrow against what you hold. The product is only as good as its edges — the moment a payment fails because the money sits in the wrong currency, users stop trusting the whole thing.

What I built

I led the React Native app alongside product, backend and QA, on a Redux Toolkit + TanStack Query architecture with per-domain service layers.

• A multi-currency wallet — crypto, NGN and USD — with on/off-ramp, crypto send and receive, currency conversion and virtual bank accounts.
• A just-in-time swap. If a payment would fail because the NGN balance is short but the user holds USDT, the app quotes and executes the conversion for just the shortfall, then completes the payment — one confirmation, not three screens.
• Crypto-backed lending with a live loan-health view.
• Recurring P2P payment requests, and merchant bill payments with real-time operator detection from the phone number.
• Authentication in layers — transaction PIN, TOTP 2FA and WebAuthn passkeys.

async function payBill(bill: Bill, amount: Naira) {
  const shortfall = amount - balances.NGN;
  if (shortfall > 0) {
    const quote = await swaps.quote({ from: "USDT", to: "NGN", amount: shortfall });
    await swaps.execute(quote, { idempotencyKey: bill.paymentId });
  }
  return bills.pay(bill, amount, { idempotencyKey: bill.paymentId });
}

Reusing the payment's idempotency key for the swap is the important line: retry the whole flow and you get the same swap, not a second one.

Outcome

• Payments that used to fail on a currency mismatch now go through in a single confirmation.
• Three authentication factors, with passkeys removing most PIN fatigue.
• One architecture across wallet, lending and payments, so features land in a known shape.