Offline-first credit management system for small retail businesses
Dube Note is a production-grade mobile application purpose-built for small retail shop owners who extend informal credit to their customers. It replaces the traditional paper-based "dube" (credit notebook) with a secure, fast, and reliable digital system that works entirely offline.
The application handles the complete credit lifecycle — from registering customers and recording individual item-level transactions, to calculating outstanding balances in real-time, settling debts, and maintaining a full payment history.
- Customer Registry — Register customers with optional payment deadlines; view all active debtors sorted by outstanding balance.
- Item-Level Transactions — Record each credit entry with item name, quantity, and unit price. Totals are computed automatically.
- Real-Time Debt Calculation — Outstanding balances are derived dynamically from unpaid transactions, eliminating desync errors inherent in manual bookkeeping.
- One-Tap Settlement — Settle a customer's full balance in a single action; all unpaid transactions transition to the paid history archive.
- 100% Offline Architecture — Zero network dependencies. No external APIs, no cloud sync, no telemetry. All data resides exclusively on the device.
- Password-Protected Access — The application is secured behind a SHA-256 hashed master password, set on first launch.
- Security Question Recovery — Forgot-password flow via two user-defined security questions (city of birth & year shop opened), with answers stored locally.
- Automatic Session Lock — Idle sessions are terminated after 5 minutes of inactivity, automatically returning to the login screen.
- Deadline Reminders — Local push notifications alert the shop owner one day before and on the day of a customer's payment deadline. Fully configured for both Android (exact alarms) and iOS (alert, badge, and sound permissions requested at runtime via
DarwinInitializationSettings). - Database Export — One-tap backup exports the raw SQLite
.dbfile via the native share sheet — send it to email, Google Drive, or any storage medium.
This screen represents the first-use flow, where the app sets up secure local access before the user enters the main credit management experience.
The same interface supports the day-to-day workflow for reviewing balances, opening customer records, and moving from active credit to paid history.
Dube Note follows a clean, layered architecture designed for maintainability and simplicity without over-engineering.
lib/
├── main.dart # App entry point, session management
├── database/
│ └── database_helper.dart # SQLite schema, CRUD operations, queries
├── models/
│ ├── customer.dart # Customer entity (name, note, deadline)
│ ├── app_transaction.dart # Transaction entity (item, qty, price, status)
│ └── user.dart # User entity (password hash, security answers)
├── services/
│ ├── auth_service.dart # Password hashing, login, setup, recovery
│ ├── backup_service.dart # Database file export via share sheet
│ └── notification_service.dart # Scheduled local notifications (timezone-aware)
├── screens/
│ ├── splash_setup_screen.dart # First-launch onboarding & password setup
│ ├── login_screen.dart # Authentication & password recovery
│ ├── dashboard_screen.dart # Main view: total debt, customer list
│ ├── customer_detail_screen.dart # Per-customer balance & transaction list
│ ├── add_transaction_screen.dart # New credit entry form
│ ├── history_screen.dart # Paid transaction archive
│ └── settings_screen.dart # Backup export & app info
└── utils/
└── theme.dart # Design system: colors, typography, components
| Layer | Technology |
|---|---|
| Framework | Flutter (Dart) |
| Local Database | sqflite / sqflite_common_ffi |
| Authentication | SHA-256 hashing via crypto |
| Notifications | flutter_local_notifications — Android (exact alarms, channels) + iOS (Darwin alerts, badge, sound) + timezone scheduling |
| Backup/Share | share_plus |
| State Mgmt | StatefulWidget + FutureBuilder (deliberately minimal, no external state libraries) |
[ Start ]
│
▼
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│ FIRST LAUNCH │ │ SETUP SCREEN │ │ DASHBOARD │
│ (Auth Check) │ ────────▶ │ (Password + SQ) │ ────────▶ │ (Customer List) │
└─────────────────┘ └─────────────────┘ └────────┬────────┘
│ │
│ (If account exists) │
▼ │
┌─────────────────┐ ┌───────────────┼───────────────┐
│ LOGIN SCREEN │ ▼ ▼ ▼
│ (Password) │ ────────▶ ┌───────────────┐ ┌───────────┐ ┌──────────┐
└─────────────────┘ │ CUSTOMER INFO │ │ HISTORY │ │ SETTINGS │
└───────┬───────┘ └───────────┘ └──────────┘
│
▼
┌───────────────┐
│ ADD TRANSAC. │
└───────────────┘
- Flutter SDK (3.11.5+)
- Android Studio or VS Code with Flutter/Dart plugins
- A physical device or emulator (Android/iOS)
# Clone the repository
git clone <repository-url>
cd dubebook
# Install dependencies
flutter pub get
# Run on Android
flutter run
# Run on iOS (requires macOS with Xcode)
cd ios && pod install && cd ..
flutter run --device-id <ios-device-or-simulator>- Set a master password — minimum 4 characters.
- Answer two security questions — city of birth and the Ethiopian calendar year your shop opened.
- Start managing credit — you'll be taken directly to the dashboard.
Your data never leaves the device. There is no account creation, no sign-up, and no internet requirement.
┌──────────┐ ┌──────────────┐ ┌──────────────┐
│ users │ │ customers │ │ transactions │
├──────────┤ ├──────────────┤ ├──────────────┤
│ id (PK) │ │ id (PK) │◄──────│ id (PK) │
│ password │ │ name │ 1:N │ customer_id │
│ _hash │ │ note │ │ item_name │
│ security │ │ deadline │ │ quantity │
│ _q1 │ │ created_at │ │ price │
│ _q2 │ │ │ │ total │
└──────────┘ └──────────────┘ │ status (0/1) │
│ date │
└──────────────┘
0 = Unpaid
1 = Paid
Dube Note uses Ethiopian Birr (ETB) as the default currency, reflecting its target market of small Ethiopian retail shops. The Ethiopian calendar is also used for the security question during setup.
Navigate to Settings → Export Local Backup to share the SQLite database file via:
- Email attachment
- Google Drive / cloud storage
- Local file transfer
The exported .db file contains all customer records, transactions, and authentication data.
- Minimal Taps — Core actions (add customer, add credit, settle debt) require the fewest possible interactions.
- High Contrast Light Theme — Optimized for outdoor readability and quick scanning in a shop environment.
- Information Hierarchy — Outstanding totals and customer names are typographically prominent; secondary data is subdued.
- Animated Transitions — Smooth fade and slide animations provide spatial context without sacrificing speed.
| Platform | Status | Notes |
|---|---|---|
| Android | ✅ Fully supported | Primary target. Exact alarm notifications, adaptive icons configured. |
| iOS | ✅ Fully supported | Darwin notification permissions (alert, badge, sound) requested at runtime. SafeArea handles notch/Dynamic Island. |
| Linux | Runs via sqflite_common_ffi. Notifications fallback to immediate display (no scheduled support). |
|
| Windows | Runs via sqflite_common_ffi. Notification scheduling not supported. |
|
| macOS | Builds but not primary target. |
Developed by WECAN TEAM
Dube Note — Digitizing trust, one transaction at a time.