UPI Tracker

It's a privacy-first Android app I built to track my UPI expenses using the UPI URI scheme and UPI deeplinks instead of bank integrations or SMS scraping.

Context and Problem

I do >90% of my transactions via UPI. Existing expense trackers want:

• KYC and bank account linking
• SMS read permissions and cloud sync

I wanted a local-only, UPI-first tracker that works entirely on top of:

• UPI QR codes
• UPI URI scheme (upi://pay)
• UPI Intent/deeplink flow to apps like Google Pay and PhonePe

No KYC, no bank APIs, no servers.

Demo

What the App Does (Technically)

Core flow:

• Scan UPI QR codes via camera → parse the UPI URI (e.g. upi://pay?pa=...&pn=...&am=...&tn=...&cu=INR).
• Extract payee UPI ID, payee name, amount, and note using a dedicated UPI parser service.
• Let me add structured metadata:
  • Category (fixed enum: Food, Utility, College, Rent, Other)
  • Reason
  • Optional description
• Launch the user’s UPI app using Android UPI Intent / deeplink integration with prefilled fields.
• Store transaction data locally in AsyncStorage with:
  • UUID, amount, UPI ID, payee, category, reason, timestamp, monthKey for grouping.
• Provide:
  • Monthly aggregation and category breakdown
  • Search across payee, UPI ID, category, reason
  • PDF export with charts using expo-print, react-native-svg, and react-native-chart-kit.

Everything is local storage + UPI URI scheme + Android Intent flow. No backend, no external APIs.

Architecture Snapshot

The app is intentionally small but structured:

• Frameworks: React Native + Expo + TypeScript, Expo Router for navigation.
• Architecture patterns:
  • Service layer pattern for business logic (storage, UPI, categories, PDF).
  • Repository-style access to AsyncStorage keys (upitracker:transactions, upitracker:categories).
  • Component composition for UI (cards, pickers, charts).

Key services:

• storage service: CRUD, monthly stats, search, delete, clear-all.
• upi-parser service: UPI URI parsing, validation, URL decoding/encoding.
• upi-launcher service: build UPI deeplink, check UPI-capable apps, fire Android Intent.
• category-storage service: enum-like category model with icon + color metadata.
• pdf-export service: HTML + SVG pie chart → PDF via expo-print → share via expo-sharing.

UI layer (Expo Router):

• Home: monthly stats, category pie chart, recent transactions.
• Scanner: full-screen camera with QR detection for UPI QR codes.
• Payment: confirm parsed UPI data + metadata, triggers UPI Intent.
• History: list + search + per-transaction delete.
• Settings: export PDF, clear-all, theme controls.

Dark-mode default with a defined theme system (tokens for colors, spacing, typography).

Process and Tooling

This app was not built from a single “generate app” prompt.

The workflow was:

• Write architecture and data-model docs first, including UPI Intent flow, AsyncStorage schema, and service boundaries.
• Use Cursor IDE + Perplexity AI in multi-turn iterations:
  • Explore UPI URI scheme edge cases and Intent behavior.
  • Refine service layer and transaction models.
  • Validate privacy-first choices (no analytics, no network).
• Then implement the app screen by screen, wired to the services already defined in docs.

UPI Tracker is essentially a concrete implementation of:

• UPI URI scheme + deeplink flow
• Local-only data architecture on AsyncStorage
• Service-layer React Native app for a single, very specific UPI expense-tracking use case

Developer

coded with ❤️ by Ayush Kansal