Farah Khoury
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Point-of-Sale & Retail Management

CTC Cashier

A production point-of-sale platform combining a C#/.NET WinForms desktop application with PHP-based backend services and management tools. My work spans transaction processing, payment-terminal integration, receipt and kitchen printing, inventory workflows, reporting, database optimization, station configuration, and WhatsApp-based document delivery.

Technologies & Integrations

C#.NETPHPMySQLBootstrapREST APIsPayment TerminalsReceipt PrintersWhatsApp API

Behind the Project

Engineering Case Study

A closer look at the engineering problems, technical decisions, responsibilities, and production challenges behind the project.

The Problem

Retail businesses require dependable transaction processing across cashier stations while coordinating payments, receipts, refunds, cancellations, inventory, reporting, hardware, and external services.

My Implementation

Developed and maintained C#/.NET POS functionality together with PHP and MySQL services. Integrated payment workflows, PAX terminals, receipt and kitchen printers, inventory operations, X/Z reporting, transaction history, WhatsApp document delivery, and station-specific configuration.

The Result

My contributions connected day-to-day POS workflows with payment hardware, printing, reporting, inventory, and digital receipt delivery. Performance and scale metrics are not published without verified data.

Engineering

Key Challenges

  • Maintaining transaction consistency across payments, refunds, cancellations, and reports
  • Supporting multiple receipt and kitchen printer configurations
  • Integrating POS workflows with external PAX payment terminals
  • Handling station-specific configuration across different customer environments
  • Maintaining transaction and refund data integrity
  • Diagnosing production issues involving software, databases, networks, and hardware
  • Securing communication between the desktop application and backend services

Ownership

My Responsibility

  • C# desktop application development
  • PHP backend development
  • REST API integration
  • MySQL database design and optimization
  • Payment-terminal integration
  • Printer and hardware integration
  • WhatsApp API integration
  • Deployment and customer configuration
  • Production debugging and technical support

Technical Overview

System Architecture

A high-level overview of the system components and how data moves between them.

STEP 01

C# POS Application

Cashiers process sales, payments, refunds, cancellations, and operational workflows through the desktop application.

STEP 02

PHP API & Services

Backend services handle business logic, communication, configuration, and shared system functionality.

STEP 03

MySQL Database

Transactions, products, inventory, reports, station information, and operational records are persisted in MySQL.

STEP 04

External Integrations

The platform communicates with PAX terminals, receipt printers, kitchen printers, WhatsApp services, and management interfaces.