zero - Minimal Expense Manager

zero is a lightweight, open-source expense tracking app for Android & iOS, built by Lossless Protocols. All your financial data stays on your device. No servers, no accounts, no analytics — the release build does not even hold the INTERNET permission.

• Play Store · App Store
• GitHub Releases — every release carries the signed APK. The GitHub APK is signed with a different key than the Play build, so one cannot be installed over the other: Settings → Export data first, uninstall, install, import.

• Releases and discussion: #zero-updates on Discord
• Bug reports: #zero-bugs on Discord or a GitHub issue
• Email: hello@lossless.dev

If zero crashes, it offers once, on the next launch, to share the error with us; nothing is sent unless you tap Share. The same log is in Settings → Diagnostics, where you can share or email it yourself. It holds error messages and code locations — never your transactions.

• Add, edit, and delete transactions with customizable categories
• Calculator in amount fields (Settings, off by default): type 120+45×2, see the result as you type
• The category of an expense you have entered before is chosen for you, from your own history, on the device
• Sort a month by date, category, title or amount

• Record money in (salary, a client, interest) and see what you received and what you kept each month
• "Got money back" on an expense: a refund counts in the month the money came back

• Home-screen widgets on Android and iOS: this month's spending, today, one tap to add
• Add an expense without opening the app: a small sheet over the home screen from the widget, a Quick Settings tile or a launcher shortcut (Android); Siri, Shortcuts or the Action Button (iOS)

Create your own categories with custom icons and colors, and drag them into the order you want.

• Monthly spending breakdown with a donut chart
• Heatmap calendar showing daily expenses
• Average per day calculations

A monthly budget with an adaptive daily allowance: what is left, divided over the days that remain.

Track money you owe or are owed, in the Money tab. Debts are what you hold and owe, not spending or income, so they never change a month's totals.

• Light & Dark themes (+ system default)
• Every ISO 4217 currency, with the symbol placed the way your locale expects
• Week starting Sunday or Monday
• Personalized username

• Export all data as JSON; import on a new device
• Export expenses as CSV
• Delete all data (with a backup offered first)

• 100% offline — no internet permission in the release build
• All data stored locally on device (SQLite)
• Zero data collection, zero crash reporters, zero analytics
• zero never reads your SMS, notifications, email, bank data, contacts or clipboard. scripts/check-no-read.mjs fails the build if any manifest, dependency, Info.plist or entitlement asks for one of them, and the release gate runs it on the built APK

• Flows and positions are different things. Spending, refunds and money in are money moving during a month; debts are what you hold and owe. A month's totals only ever count the first.
• One table per fact. Expenses, refunds, money in and debts live in their own tables; a row's table says what it is.
• Derive, never store. Spent, received and kept are computed when you look, never kept in a running total that could drift.
• Amounts are positive; the table gives the direction. Sums run in integers, so ₹0.10 + ₹0.20 is ₹0.30.
• Adding an expense stays fast. The add-expense flow keeps the same taps in every version.
• Your data, your device. Backups are plain JSON files you keep; nothing leaves the phone unless you share it.

We migrated from Realm to WatermelonDB because:

• Realm is deprecated — MongoDB announced end of support
• SQLite is battle-tested — Powers millions of apps
• Lazy loading — Only loads data when needed
• Better React Native integration — Built specifically for RN
• Smaller bundle size — Less bloat

Lowest layer first. A module imports only from its own layer or a lower one, and no feature imports another feature. dependency-cruiser enforces it on every test run (.dependency-cruiser.cjs holds the rules; bun run check:layers), and knip finds anything unused (bun run check:exports). Native code, the widgets and the generated assets are mapped in docs/NATIVE.md; tests live in one tree, __tests__/.

src/
├── domain/            # Pure rules and types: money units, day keys, period, budget and debt maths
├── constants/         # Outbound links
├── platform/          # The device: MMKV storage and preferences, locale and formatting, error log
├── i18n/              # Strings and validation messages
├── data/              # The data layer
│   ├── database/      # WatermelonDB schema, migrations, models, v5 backfill, seeded defaults
│   ├── services/      # Every read and write, each enforcing its own invariants
│   ├── dataMigrations/# Sequential data migrations run at start
│   ├── backup/        # Export format, upgrader, validation, import planner, file IO
│   └── startup.ts     # Opens the database and runs pending migrations
├── native/            # TurboModule specs (codegen); only features/widgets/bridge.ts uses them
├── store/             # Redux Toolkit: slices, session start (bootstrapSession), middleware
├── ui/                # Shared view code: hooks and contexts → atoms → molecules → sheets
├── features/          # One product area each: lib → hooks → components → sheets → screens
│   ├── spending/      # Home, the day and category lists, add/edit expense, refunds
│   ├── money/         # The Money tab: money in and debts
│   ├── categories/    # The Categories tab, add/edit, icon and colour pickers
│   ├── reports/       # Reports: donut, heatmap, money-in strip
│   ├── settings/      # Settings, Diagnostics, preference pickers
│   ├── onboarding/    # Splash, welcome, name, categories, currency, restore
│   └── widgets/       # Home-screen widget snapshot, the Siri/widget queue, the quick-add sheet
└── navigation/        # The app shell: stacks, deep links, the sheet registry

__tests__/             # Every test, by kind: unit/ and component/ mirror src/ (see its README)
contracts/             # Fixtures the JS, Kotlin and Swift sides all read

• Node.js >= 22.13
• Bun (package manager)
• Android Studio / Xcode 16.1+

git clone https://github.com/lossless-protocols-org/zero.git
cd zero
bun install

# iOS only
cd ios && pod install && cd ..

bun run android   # or bun run ios
bun run typecheck # tsc --strict
bun run test      # jest (every suite but the SQLite ones)
bun run test:sqlite # bun: WatermelonDB's SQL on real SQLite
bun run check     # the whole JS gate, as CI runs it

zero is developed in-house at Lossless and stays deliberately small, so pull requests are not accepted. Bug reports and ideas are very welcome — on Discord, in GitHub issues, or by email. Please read the Code of Conduct.

• Privacy Policy — zero collects nothing; the page itemizes the nothing
• Terms

zero is free software, licensed under the GNU General Public License, version 3 or later. You may use, study, change and share it; if you distribute a changed version, you must publish its source under the same licence.

• The names "zero" and "Lossless", the icon, the logo and the store artwork are not covered by that licence. A changed version needs its own name and artwork. See NOTICE.
• Version 2.8.0 and earlier were published under the BSD 2-Clause License, which still applies to those versions.