Cardly

Inspiration

Most people carry 3+ credit cards and 8+ subscriptions — yet have no single place to track due dates or recurring charges. Late fees and forgotten subscriptions silently drain hundreds of dollars a year. We built Cardly to fix that.

What it does

Cardly tracks credit card billing cycles with smart repayment reminders, aggregates all subscriptions with renewal alerts, and lets users log daily expenses via a calculator-style quick-entry interface — all offline, no bank account required.

How we built it

React Native + Expo (iOS), TypeScript, NativeWind for styling, Zustand for state, expo-sqlite + Drizzle ORM for local-first data, and expo-notifications for scheduled repayment reminders. Designed and prototyped 18 screens end-to-end.

Challenges we ran into

Modeling credit card billing cycles (statement date ≠ due date), designing frictionless manual input without bank sync, and building a calm, trustworthy UI for an anxiety-prone domain.

Accomplishments that we're proud of

18 fully interactive screens shipped in one hackathon cycle. A privacy-first architecture that requires zero bank credentials while still delivering genuine financial utility from day one.

What we learned

Manual input can be a feature, not a limitation. Users who intentionally log their finances develop stronger spending awareness than those who passively consume auto-imported data.

What's next for Cardly

Native iOS push notifications, optional Plaid integration for subscription auto-detection, a couples/household shared mode, and a Pro tier at $4.99/month targeting 10,000 paying users in year one.

Built With

• codex
• ios
• javascript
• orm
• react