SpentSmart

SHIPPED

A privacy-first Android UPI expense tracker with a custom Kotlin native module and no backend.

Personal project · Jan–Feb 2026 · 65 commits

THE PROBLEM

Expense trackers usually read SMS or link bank accounts. Track UPI payments without either, and keep all data on the device.

HOW IT WORKS

A Kotlin Expo module queries PackageManager for UPI apps and launches them by package, and shares QR images through a FileProvider.
Data lives in local storage behind an optional biometric lock. A pending-payment flow watches deep links and the clipboard, and asks the user to confirm.

SCREENSHOTS

Captured from the project's own repository. Select an image to open it full size.

ENGINEERING EVIDENCE

Three APK releases (v1.0.0, v2.0.0, v2.01) on GitHub Releases.
Nine phone screenshots are in the repository README.

The documented 45MB-to-15MB size cut is not visible: release APKs grew 9.3%REJECTED
No reduction is visible: the v2.0.0 and v2.01 APKs are about 9.3% larger than v1.0.0.
Replay a scanned merchant QR's original parameters instead of rebuilding the UPI URLADOPTED
According to docs/UPI_FIXES_APPLIED.md, the first version never returned rawParams, so every scan fell back to a rebuilt URL.
Custom Kotlin Expo module with <queries> to find and launch UPI apps on Android 11+ADOPTED
Needs a development build (QRPaymentGenerator.tsx logs 'UpiIntent native module not available (Expo Go)').

WHAT ISN'T DONE

No automated tests.
Payment "verification" is a time-based confidence heuristic, not real payment status.
Android only.

STACK

React Native
Expo
TypeScript
Kotlin