Expense Tracker
A premium offline-first personal finance and expense tracking application available on Android and Windows Desktop.
Our Role
Native Android & Desktop Developer, UI/UX Designer, Database Architect
Technologies & Frameworks
Project Overview
Expense Tracker (v5.0.0) is a premium, offline-first personal finance and wealth management application developed natively for the Android platform. By running 100% locally and device-bound, it guarantees absolute privacy for the user's financial ledger. The application allows users to orchestrate their budgets, manage multiple accounts/wallets (like Cash, Credit Cards, Bank Accounts, and Savings), log transactions with an integrated arithmetic calculator, track loans and borrowing, and schedule recurring expenses or income. The application is built on modern Android development standards, utilizing Jetpack Compose for reactive, declarative layouts, Kotlin Coroutines & Flow for asynchronous stream handling, Room Database for persistent storage, and local biometric sensors for hardware-level app lock security.
The Challenge & Problem
- Modern personal finance applications heavily depend on cloud servers, requiring constant internet connectivity, exposing sensitive financial logs to data breaches, and forcing users to link their private bank credentials.
- Manual entry interfaces introduce high friction: standard numeric keypads force users to bounce back and forth to external calculator apps to compute shared bills or split costs, and fixed calendar budgets fail to align with real-world, non-monthly payroll cycles.
The Engineering Solution
- Developed a native Android app that runs entirely offline, storing data locally inside a secured SQLite database.
- The project introduces an integrated arithmetic compiler directly inside the transaction input keyboard (enabling operations like 250 + 120 * 1.05), allowing users to split and compute expenses inline.
- The application supports custom budget periods (Weekly, Monthly, or Custom Date Ranges) that sync with the user's real payroll cycles, and protects all sensitive data behind local biometric authentication and a fast screen-masking privacy mode.
Key Architecture & Features
Dynamic Dashboard & Budget Controller
- High-visibility spending indicators displaying remaining funds relative to budget intervals (Weekly, Monthly, Custom) along with smooth, interactive 7-day spending line charts.
Multi-Wallet Account System
- Creation and customization of distinct financial pools (Cash, Credit Cards, Savings) with custom color hexes, bank names, starting balances, and icons. Balances automatically adjust during inter-account transfers.
Arithmetic Input Parser
- An inline math evaluation keyboard that parses arithmetic strings directly in the transaction amount field, displaying a live preview prior to confirmation.
Planned Transactions & Automation
- Cycle-based planners (Daily, Weekly, Monthly, Yearly) for fixed bills and recurring subscriptions. Automatically triggers income deposits in the background and highlights overdue bills in red.
Lending & Borrowing Ledger
- Track debts (what you owe) and dues (what others owe you) linked to contacts, with due dates and a toggle to log payments directly to the main transaction history.
Advanced Filtering & Tag Search
- Multi-criteria transaction history lookup enabling searches by description, category, tags, and date ranges.
Privacy Masking Mode
- One-tap toggle that masks balances and income (displaying them as ••••) to prevent shoulder-surfing in public.
Hardware Biometric Lock
- Security integration leveraging fingerprint/facial recognition to lock financial logs.
Data Portability & Local Backups
- JSON and CSV export/import systems, Excel workbook creation using Apache POI, and native PDF invoice printing.