An offline-first personal finance tracker for Android. Log expenses in seconds by tapping or just speaking, see where your money goes, stay within budget and track loans to the last EMI. All data stays on your phone; voice entry is optional and, when used, sends only the recording plus your category and account names to Gemini.
- Expense, income and transfer entries with a built-in calculator keypad (
40+7,2×120, …) - Two-tap categorisation: pick a category, then a subcategory (e.g. Dairy → Milk)
- Quick date chips (Today / Yesterday) plus a native date picker
- + Next to log several items in a row without leaving the screen
- Notes, edit, and delete with confirmation
- Month-by-month timeline grouped by day with daily totals
- Hold the mic, say "milk 47, petrol 205 yesterday, salary 60000 to savings", release
- Google Gemini turns speech into entries with the right category, subcategory, account and date ("yesterday", "last Friday", "on the 5th")
- Review screen before anything is saved: fix or remove entries, then save all at once
- Uses your own free Gemini API key, set up in Settings → Voice entry. The key is checked with Google before it's saved and stored encrypted on the phone, never in backups
- Clear messages for a wrong or expired key, used-up daily limit, no internet and busy servers
- Monthly and yearly views with income, expense and savings
- Donut chart by category; tap a category to see its subcategory split
- Per-category monthly budgets with progress bars (green → amber → red)
- Month-by-month income vs expense bars for the year
- Bank accounts, cash, wallets, credit cards and your own custom types, all created by the user
- Credit card dues shown as the amount owed
- Live balances, net worth, assets vs liabilities
- Transfers between accounts; balance corrections are recorded as adjustments, never silent edits
- Hide accounts you no longer use without losing history
- Dedicated tab with outstanding amount, % repaid and projected payoff month
- Pay EMI pre-fills a transfer from your bank to the loan
- Monthly interest is posted automatically at month end on the outstanding balance (reducing-balance method)
- Ships with a clean, standard set (Dairy, Meat & Eggs, Groceries, Bills & Utilities, Vehicle, …)
- Add, rename, hide or delete categories and subcategories, and set budgets
- Items in use can only be hidden, so history is never orphaned
- Search across notes, categories, accounts and amounts, with filters for date range, type, account and category
- Backup to Google Drive (or anywhere) through the Android share sheet, and restore from a backup file
- CSV export for spreadsheets, and CSV import with automatic matching and duplicate detection
- Every destructive action asks for confirmation first
| Area | Choice |
|---|---|
| Framework | Expo SDK 58, React Native 0.88, React 19 |
| Language | TypeScript (strict) |
| Navigation | Expo Router (file-based, tabs + modal stack) |
| State | Zustand |
| Storage | Single JSON file via expo-file-system (no database) |
| Charts | react-native-svg (hand-built donut and bar charts) |
| Files | expo-sharing, expo-document-picker |
| Native UI | @react-native-community/datetimepicker, expo-haptics |
| Voice | expo-audio (recording), Gemini API (generateContent with audio input and JSON schema output), expo-secure-store (API key) |
| Testing | Node assert + tsx (unit), Playwright (end-to-end on the web build) |
| Tooling | ESLint (eslint-config-expo), Prettier |
- Money is stored as integer paise. No floating-point drift in balances or interest.
- Dates are local
YYYY-MM-DDstrings. Using UTC timestamps in IST would push anything before 05:30 into the previous day. - Storage is one compact file. Writes go to a temp file that is then atomically renamed, and the previous version is kept as a fallback. If the file can't be read, the app refuses to overwrite it and asks you to restore. Two years of daily entries is about 200 KB.
- Saves are debounced and also flushed when the app goes to the background.
- Cash-flow rules for stats:
- Transfers between your own accounts are not spending.
- Payments into a loan count as loan spending.
- Interest posted on the loan account doesn't touch your cash, so it isn't double-counted.
- Balance adjustments are excluded.
- Pure core. All business logic lives in
src/lib/ledger.tsas pure functions over plain data, and the store is a thin wrapper. That's what makes it fully unit-testable.
src/
├── app/ Expo Router screens
│ ├── (tabs)/ Transactions, Stats, Accounts, Loans, Settings
│ ├── account/ Account detail and editor
│ ├── category/ Category editor
│ ├── categories.tsx Category list
│ ├── search.tsx Search and filters
│ ├── tx.tsx Add / edit transaction (modal)
│ ├── voice.tsx Review entries from voice
│ └── voice-settings.tsx Gemini API key setup
├── components/
│ ├── ui.tsx Theme tokens and shared UI primitives
│ └── VoiceButton.tsx Hold-to-talk recorder
└── lib/
├── ai.ts Gemini request, reply parsing, key checks, error messages
├── voice.ts API key storage, audio file reading
├── ledger.ts Validation, balances, cash flows, loan interest, CRUD
├── store.ts Zustand store + file persistence
├── csv.ts CSV parse / export / import
├── io.ts Backup, restore, share, file picking
├── money.ts Formatting (₹ Indian grouping), calculator, date helpers
├── seed.ts Default categories
└── types.ts Data model
scripts/e2e.mjs End-to-end UI test
Download SmartWallet-vX.Y.Z.apk from Releases on your Android phone (Android 7.0+, arm64) and open it to install. Updating to a newer release keeps your data.
Requirements: Node 20+, and either an Android phone with Expo Go or the Android SDK for native builds.
git clone https://github.com/thekirankumarv/SmartWallet.git
cd SmartWallet
npm install
npm start # scan the QR code with Expo Go
npm run web # or run in the browserRequires the Android SDK and JDK 17+ (ANDROID_HOME and JAVA_HOME set).
npm run apk # outputs SmartWallet.apk in the project rootThe release build targets arm64-v8a with R8 minification and resource shrinking (~17 MB).
npm test # unit tests: calculator, formatting, dates, CSV, ledger, loan interest, voice parsing and API errors
npm run e2e # UI flow test (start `npm run web` first; run `npx playwright install chromium` once)
npm run typecheck
npm run lintThe end-to-end suite starts from a fresh install and walks through:
- creating accounts
- adding, editing and deleting transactions (cancel and confirm)
- transfers and income
- adding a loan and paying an EMI
- stats
- the guards that stop deleting accounts and categories still in use
- category and subcategory management
- search
- voice entry setup (key format and rejected-key messages) and the review screen
- data surviving a reload
Export and import use the same columns:
Date,Time,Type,Account,To Account,Category,Subcategory,Note,Amount
2026-10-24,08:15,Expense,HDFC Bank,,Dairy,Milk,,56
2026-10-01,,Income,HDFC Bank,,Salary,,,85000
2026-10-05,,Transfer,HDFC Bank,Home Loan,,,,21500- Required columns:
Date,Account,Type(Expense/Income/Transfer) andAmount. - Dates:
YYYY-MM-DDorDD/MM/YYYY. - Matching: accounts, categories and subcategories are matched by name (case and punctuation insensitive). Missing ones are created.
- Duplicates: rows already in the app are skipped, so re-importing the same file is safe.
MIT © Kiran Kumar V