Custom POS System
Modern Point-of-Sale with Offline Capability and Inventory Management
The Context
What problem we set out to solve
Small retail businesses often rely on outdated POS systems that are slow, unreliable, or require expensive vendor lock-in. When internet goes down, many cloud-based POS systems become unusable - costing businesses real sales.
This project demonstrates a modern POS system built with offline-first architecture. It continues working during network outages, syncing automatically when connectivity returns. The goal was to create a reference implementation showing how retail software should work in the real world.
While this is a demo system, it represents production-ready architecture that can be customized for specific retail, restaurant, or service business needs.
The Constraints
What made this challenging
Offline-First Architecture
The system must work 100% offline with seamless sync when connectivity returns - no lost sales, no data corruption, no user frustration.
Fast Checkout Experience
Every transaction needs to complete in under 3 seconds. Slow POS systems cost retailers real money during busy periods.
Multi-Location Ready
Architecture designed to support multiple locations with centralized inventory management and sales reporting.
Secure by Default
Role-based access control, audit logging, and secure local data storage. No shortcuts on security, even for a demo.
The Solution
How we built it
Core Features
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Offline-First Checkout - Uses IndexedDB for local storage with background sync. Transactions are never lost, even during outages.
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Real-Time Inventory - Stock levels update across all terminals instantly. Low stock alerts prevent out-of-stock surprises.
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Quick Product Search - Type-ahead search with barcode scanner support. Find any product in milliseconds.
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Sales Analytics Dashboard - Daily, weekly, and monthly sales reports. Track best sellers, slow movers, and revenue trends.
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Role-Based Access - Cashiers, managers, and admins see appropriate features. Full audit trail for accountability.
Tech Stack
Built for reliability and speed
Frontend
- React 18
- Tailwind CSS
- IndexedDB (Dexie.js)
- Service Workers
Backend
- Node.js / Express
- SQLite (local)
- PostgreSQL (cloud sync)
- REST API
Offline Sync
- Background Sync API
- Conflict Resolution
- Queue-based Uploads
Infrastructure
- PWA (Progressive Web App)
- Can run on any device
- No app store needed
What I'd Improve Next
Honest assessment of where this could go
Payment Integration
Currently demo-only. Production version would integrate with Stripe Terminal, Square, or other payment processors for real card processing.
Customer Loyalty
Add customer accounts, points tracking, and loyalty rewards. This drives repeat business and increases average order value.
Mobile Companion App
Native mobile app for inventory scanning and quick price lookups. Especially useful for businesses with large floor space.
Hardware Integration
Receipt printer, cash drawer, and barcode scanner drivers. Current demo uses browser-based fallbacks.
Multi-Location Sync
The architecture supports it, but would need production testing with real multi-location data flows and conflict resolution edge cases.
Reporting Export
Add CSV/PDF export for sales reports and inventory snapshots. Integration with accounting software (QuickBooks, Xero).
The Outcome
What this project demonstrates
This demo showcases our ability to build production-grade business software. The offline-first architecture, real-time sync, and clean UX represent the quality we bring to every client project. Ready to customize for your specific retail, restaurant, or service business needs.
Need a Custom Business System?
Whether you need a POS, inventory system, or custom business application - we can build it to your exact specifications.