RetailFlow POS — Case Study

The Challenge

The client relied on paper logs and a legacy desktop app that couldn’t sync across stores. This caused:

22% average stockout rate on high-turnover items
40+ hours/week spent on manual reconciliation
No real-time visibility into sales or inventory
Frequent downtime during internet outages

They needed a resilient, modern POS that worked today — without disrupting daily operations.

Our Approach

We designed a hybrid LAN/cloud architecture to ensure uptime, data integrity, and scalability:

Offline-first operation: Process sales even during outages
Real-time sync: Changes propagate across locations within 60s
Thermal printer abstraction: Support for 8+ printer models
Role-based access: Cashier, Manager, Admin permissions

System Architecture

Key insight: Local SQLite ensures uptime; cloud PostgreSQL enables cross-store analytics and backups.

Key Screenshots

Login & Dashboard

Secure login and real-time sales/inventory overview.

Checkout Flow

Intuitive barcode scanning and split-payment support.

Inventory Management

Track stock levels, receive alerts, and manage suppliers.

Receipt Generation

Professional thermal receipt printing with store branding.

Measurable Impact

37%

↓ in average queue time

$18k/yr

Saved in labor costs

99.2%

Inventory accuracy

The system was deployed across all 12 locations in 8 weeks — with zero downtime during cutover.

Tech Deep Dive

Core Stack & Key Decisions

▼

Node.js 18 Electron React 18 SQLite PostgreSQL AWS EC2/RDS

Why SQLite locally? Zero-config, file-based DB ensures offline operation. Data syncs to cloud PostgreSQL for analytics.

Electron over web? Direct hardware access (printers, barcode scanners) without browser limitations.

Sync Strategy (Critical Path)

▼

We implemented a conflict-free replicated data type (CRDT-inspired) sync queue:

// Local store pushes to sync queue on mutation
db.run(`INSERT INTO sync_queue (table, action, payload, timestamp) 
        VALUES (?, ?, ?, ?)`, 
  ['sales', 'INSERT', JSON.stringify(sale), Date.now()]);
                        

Cloud pulls every 60s, applies changes, and broadcasts to other stores. Conflicts are resolved by timestamp + store priority.

Thermal Printer Abstraction Layer

▼

Created a unified interface to support 8+ printer models (Epson, Star, Bixolon):

class ThermalPrinter {
  constructor(model) {
    this.driver = PrinterDrivers.get(model); // Factory pattern
  }
  
  printReceipt(sale) {
    const commands = this.driver.generateESCPOS(sale);
    this.driver.send(commands);
  }
}
                        

This reduced integration time for new hardware from 3 days → 2 hours.

Client Voice

“dingi.co delivered a system that just works — even during internet outages. Our staff adopted it in 2 days, and we’ve eliminated stockouts completely. Worth every penny.”

— Operations Director, Regional Pharmacy Chain

Lessons Learned

Would integrate audit logging from Day 1 — crucial for financial reconciliation
Thermal printer drivers vary wildly — build the abstraction layer before UI work
Staff training is 50% of adoption — we now include video walkthroughs in deployment

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