Koin — Personal Finance Tracker
Mobile-first expense tracking app with SMS auto-parsing, budget analytics, and intelligent categorization.
Solo Developer
3 Months
React Native, Expo, TypeScript
Mobile Architecture
The Challenge
Parsing diverse SMS formats from multiple banks, implementing reliable pattern matching for transaction categorization, and building a performant mobile UI that handles thousands of transactions without lag.
Architectural Decisions
◆SMS Parsing Engine
Built a regex-based parsing engine that handles 20+ bank SMS formats, extracting amount, merchant, and transaction type automatically.
◆Offline-First Design
Local SQLite storage with background sync ensures the app works seamlessly without network connectivity.
◆Smart Categorization
Pattern-matching algorithm that learns from user corrections and auto-categorizes recurring transactions.
◆Performance Optimized
Virtualized lists with lazy loading and memoized chart components for buttery-smooth scrolling through thousands of entries.