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sandeepkumar0801/README.md

Hello, I'm Sandeep Kumar

Senior .NET Developer | Senior Architect | Full-Stack Developer | 15+ Years Experience

Contact Information:

Email Upwork

Transforming business ideas into scalable, enterprise-grade solutions


Professional Overview

With over 15 years of hands-on experience in software development and architecture, I specialize in building enterprise-grade applications that serve millions of users. My expertise spans the entire technology stack, from database design to cloud deployment, with a proven track record of delivering mission-critical systems that handle over 100,000 daily requests with 99.9% uptime.

Core Expertise

  • Enterprise Architecture: Designing scalable, maintainable systems that grow with business needs
  • API Development: Creating robust RESTful APIs with comprehensive documentation
  • Travel Technology: Building booking systems, supplier integrations, and real-time processing solutions
  • Cloud Solutions: Deploying and optimizing applications on Azure and AWS platforms
  • Team Leadership: Successfully leading development teams of 5-15 developers
  • Security: Implementing JWT, OAuth, and certificate-based authentication systems

Technology Stack

Backend Development

C# .NET ASP.NET Core Node.js Python Hangfire Express.js

Databases & Storage

SQL Server MySQL PostgreSQL SQLite MongoDB Redis Access

Cloud & DevOps

Azure Azure DevOps Azure Batch Docker Render

Frontend & Mobile

React Next.js Vue.js Nuxt.js Angular TypeScript Tailwind CSS Vite Streamlit

Desktop & Enterprise Tools

Windows Forms WPF Entity Framework JWT Swagger

E-commerce & Marketplace APIs

Amazon Shopify WooCommerce Magento PrestaShop eBay Mirakl BlueDart DTDC

AI & Analytics

OpenAI Plotly TradingView GSAP


Professional Highlights

Metric Achievement Impact
Experience 15+ Years Senior Full-Stack Architect
Team Leadership 5-15 Developers Multiple Successful Deliveries
Daily API Requests 100K+ Handled High-Performance Travel Systems
System Uptime 99.9% SLA Mission-Critical Reliability
API Integrations 20+ Travel Suppliers Complex Multi-Vendor Systems
Hotel Processing 10K+ Daily Rebookings RebookingAtLowerCostEngine
Railway Operations Multi-Station IPIS Real-Time Passenger Information
Cost Savings 15-30% via RebookingAtLowerCostEngine Intelligent Booking Algorithms
Global Reach 100+ Cities Served International Travel Platforms
Architecture Microservices & Clean Code Scalable Enterprise Solutions
Cloud Deployment Azure & Multi-Environment DevOps & Infrastructure as Code
Project Portfolio 8+ Major Systems Travel, Logistics, Finance, Railway

Project Portfolio Overview

Travel & Tourism Technology

Enterprise booking API serving over 100,000 daily requests

This comprehensive travel booking system powers multiple production websites including www.hop-on-hop-off-bus.com. Built with .NET 6, it integrates with over 20 major travel suppliers including Tiqets, Bokun, BigBus, HotelBeds, and GetYourGuide.

Key Features:

  • Real-time booking and availability checking
  • Multi-language support for international customers
  • Automated voucher generation and delivery
  • Background processing with Hangfire
  • Comprehensive caching layer using Redis
  • Clean architecture with extensive testing

Technical Implementation:

  • .NET Core backend
  • RESTful APIs with Swagger documentation
  • JWT authentication and rate limiting
  • SQL Server for data persistence
  • Azure cloud deployment
  • Entity Framework Core for data access

Advanced hotel pricing optimization and automated rebooking system

This intelligent system processes over 10,000 hotel reservations daily, continuously monitoring prices across multiple suppliers to automatically rebook customers at lower rates, achieving 15-30% cost savings.

Key Features:

  • Multi-supplier price comparison algorithms
  • Automated rebooking at lower costs
  • Machine learning-based optimization
  • Real-time price monitoring
  • Dynamic pricing algorithms

Technical Implementation:

  • .NET Core backend with Azure Batch processing
  • SQL Server and MongoDB for data storage
  • Hangfire for background job processing
  • Redis for high-performance caching
  • Integration with multiple hotel booking APIs
  • Comprehensive notification systems

Comprehensive multi-tenant property and facility management platform

An enterprise-grade system supporting over 50 properties and 1000+ facilities with complete management capabilities.

Key Features:

  • Multi-tenant architecture for scalability
  • Gate management and access control
  • Inventory tracking and management
  • Advanced reporting and analytics
  • Responsive frontend interface

Technical Implementation:

  • .NET Core backend with SQL Server
  • Angular 15+ frontend framework
  • Docker containerization
  • Azure DevOps for CI/CD
  • Multiple deployment environments (Belt, Karamat, Leather)

Luxury resort and hospitality website with modern design

A high-performance resort website featuring modern design principles and achieving 95+ Lighthouse performance scores.

Key Features:

  • Responsive design for all devices
  • Interactive image galleries
  • Amenities showcase and booking
  • Contact management system
  • Smooth animations and transitions

Technical Implementation:

  • Next.js 13+ with React 18
  • TypeScript for type safety
  • Tailwind CSS for styling
  • GSAP for animations
  • Static site generation for performance
  • Render.com deployment with CDN

Comprehensive railway operations and passenger information system

A complete railway management solution handling operations across multiple stations with real-time passenger information and multi-language announcements.

Key Features:

  • Train scheduling and management
  • Station operations control
  • Passenger information system (IPIS)
  • Multi-language voice announcements
  • Real-time status updates

Technical Implementation:

  • .NET Framework with Windows Forms
  • SQLite and Access Database integration
  • Web API for external integrations
  • Audio system integration
  • Desktop applications for station management
  • 100+ pre-recorded announcements in multiple languages

Enterprise & Logistics Solutions

Enterprise multi-marketplace synchronization and logistics platform

  • Backend: Node.js, Express.js, MySQL, JWT authentication, comprehensive Swagger API documentation
  • Frontend: React 18, Vite, Tailwind CSS, responsive design with real-time updates
  • Architecture: Microservices architecture with separate frontend/backend, automated cron jobs, error management

πŸ”— Marketplace & Shipping API Integrations:

E-commerce Platforms:

Shipping & Logistics APIs:

Core Functionalities:

  • Product Synchronization: Bi-directional sync across all marketplaces with variant support
  • Inventory Management: Real-time stock updates, low-stock alerts, automated reordering
  • Order Processing: Centralized order management, status updates, automated fulfillment
  • Price Management: Dynamic pricing, bulk price updates, marketplace-specific pricing
  • Tracking Integration: Multi-carrier tracking, automated status updates, customer notifications
  • Error Management: Comprehensive error logging, retry mechanisms, alert systems
  • Cron Automation: Scheduled sync jobs, automated data processing, background tasks

Scale & Performance:

  • Multi-tenant architecture supporting 100+ clients simultaneously
  • Real-time synchronization across 8+ major marketplaces
  • Automated processing of 10,000+ products and orders daily
  • Comprehensive API documentation with 150+ endpoints
  • Advanced error handling with retry logic and alert management

Modern web application with Vue.js ecosystem

  • Tech Stack: Vue.js 3, Nuxt.js 3, TypeScript, Tailwind CSS, Vite
  • Features: Server-side rendering, responsive design, modern UI/UX, PWA capabilities
  • Deployment: Azure Static Web Apps with automated CI/CD pipelines
  • Performance: Optimized build process, lazy loading, and efficient asset management

Infrastructure as Code for multiple production environments

  • Tech Stack: Azure DevOps, YAML pipelines, ARM templates, PowerShell scripts
  • Environments: Multiple PMS environments (Belt, Karamat, Leather) with environment-specific configurations
  • Features: Automated deployments, database migrations, frontend builds, rollback capabilities
  • Scale: Manages infrastructure for 10+ production applications with zero-downtime deployments

AI & Financial Technology

AI-powered trading platform with real-time analytics

  • Tech Stack: Python 3.11+, Streamlit, OpenAI GPT-4, Kite Connect API, Plotly
  • Features: Real-time portfolio analytics, AI investment recommendations, automated trading
  • AI Integration: OpenAI GPT-4 for market analysis, sentiment analysis, portfolio optimization
  • Scale: High-frequency data processing, real-time price streaming, WebSocket connections
  • Security: OAuth integration, secure credential management, session persistence
  • Visualization: Interactive TradingView charts, custom dashboards, performance metrics

Development Tools & Infrastructure

Comprehensive development and debugging toolkit

  • Tools: JetBrains dotPeek, dnSpy, Database engines, Migration utilities
  • Purpose: Code analysis, reverse engineering, database management, debugging
  • Utilities: Access database engine, MySQL to SQL Server migration tools
  • Databases: SQL Server, MySQL, PostgreSQL, SQLite, MongoDB support

Technology Portfolio & Analytics

** Project Technology Distribution**

Technology Projects Repository/Project Names Expertise Level
C# / .NET 5 Projects ToursAndActivities, RebookingAtLowerCostEngine, PMS, Railway IPIS, Development Tools ⭐⭐⭐⭐⭐ Expert
SQL Server / MySQL 5 Projects ToursAndActivities, RebookingAtLowerCostEngine, PMS, Railway IPIS, Logistics System ⭐⭐⭐⭐⭐ Expert
JavaScript/Node.js 3 Projects Logistics System, Lumora Resort, DigispinWeb ⭐⭐⭐ Intermediate
React/Next.js 2 Projects Lumora Resort, Logistics System ⭐⭐⭐ Intermediate
Vue.js/Nuxt.js 2 Projects RebookingAtLowerCostEngine, DigispinWeb Platform ⭐⭐⭐ Intermediate
Angular 1 Project Property Management System (PMS) ⭐⭐⭐ Intermediate
Python 1 Project Zerodha Trading Platform ⭐⭐ Basic
Azure 5 Projects ToursAndActivities, RebookingAtLowerCostEngine, PMS, DigispinWeb, Azure IaC ⭐⭐⭐⭐ Advanced
AWS 2 Projects Channel Connector (Lambda, S3, EC2), Amazon Selling Partner API Integration ⭐⭐⭐ Intermediate
Redis 2 Projects ToursAndActivities, RebookingAtLowerCostEngine ⭐⭐⭐⭐ Advanced

** Project Complexity & Scale**

Enterprise Projects API Integrations Daily Requests Production Systems

** Domain Expertise**

Domain Proficiency Projects
Travel & Tourism Technology β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 100% 4 Projects (ToursAndActivities, RebookingAtLowerCostEngine, PMS, Railway IPIS)
Enterprise Logistics β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 100% 1 Major System (Channel Connector)
Financial Technology β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 80% 1 Advanced Platform (Zerodha Trading)
Railway Management Systems β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 100% 1 Comprehensive System (IPIS)
E-commerce Integrations β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 100% 7 API Integrations (Amazon, Shopify, eBay, WooCommerce, Magento, PrestaShop, Mirakl)
Cloud Infrastructure β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 100% 5 Azure Projects (ToursAndActivities, RebookingEngine, PMS, DigispinWeb, Azure IaC)
Web Development β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ 100% 3 Projects (Lumora Resort, DigispinWeb, Development Tools)

What Sets Me Apart

Business-Focused Development

I don't just write codeβ€”I solve business problems. Every solution I build is designed with ROI, scalability, and maintainability in mind.

Proven Track Record

  • 15+ years of consistent delivery
  • 50+ successful projects across various industries
  • Zero critical production failures in the last 5 years
  • 100% client satisfaction rate on Upwork

Full-Stack Expertise

From database design to user interface, I handle every aspect of application development with equal proficiency.

Leadership & Mentoring

Successfully led development teams, mentored junior developers, and established coding standards that improved team productivity by 40%.


Let's Build Something Amazing Together

I'm passionate about transforming complex business requirements into elegant, scalable solutions. Whether you need:

  • Enterprise Architecture - Designing systems that scale
  • API Development - Building robust, documented APIs
  • Travel Technology - Booking systems and integrations
  • Cloud Migration - Moving to Azure/AWS
  • Team Leadership - Leading development initiatives
  • Legacy Modernization - Upgrading existing systems

I deliver enterprise-grade solutions with clean code, comprehensive documentation, and measurable business impact.


Available for freelance projects | [email protected]

Hire Me on Upwork

** Ready to discuss your next project? Let's connect!**

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