Rajat K.

Need a Senior .NET Developer to **build, fix, modernize, optimize, or scale your application?** I’m a Senior .NET Developer with 10+ years of experience helping startups, SaaS companies, and enterprises build reliable software, modernize existing systems, resolve complex technical issues, and deliver scalable business applications. ⭐ Top Rated Plus | 100% Job Success | 5.0 Rating | 75 Jobs | 6.1K+ Hours From developing a new SaaS platform to debugging a legacy application or optimizing a slow API, I can take ownership of your project from technical planning through development, deployment, and ongoing support. 🚀 Core Services ✅ .NET & C# Development * ASP.NET Core, .NET 8/9/10, MVC, and Web API * Custom web applications and enterprise software * SaaS platforms, ERP, and CRM solutions * Legacy .NET application modernization and migration ✅ API Development & Integrations * REST API design and development * Third-party API and system integrations * Microservices and distributed applications * Authentication, authorization, JWT, and OAuth * API debugging, security, and performance optimization ✅ Bug Fixing & Application Optimization * Complex production issues and debugging * Slow APIs, database bottlenecks, and performance problems * Code refactoring and technical debt reduction * Existing application enhancements and feature development * Stability, reliability, and security improvements ✅ Microsoft Azure & DevOps * Azure App Services, Functions, and Service Bus * Azure Storage and Key Vault * Cloud migration, deployment, and configuration * Docker, CI/CD, GitHub Actions, and Azure DevOps * Application monitoring and production troubleshooting ✅ Database Development * SQL Server and PostgreSQL * Entity Framework Core and Dapper * Database architecture and schema design * Query optimization, indexing, and stored procedures * Caching and data-access performance improvements ✅ AI & LLM Integration * OpenAI and Azure OpenAI APIs * AI chatbots and intelligent assistants * Retrieval-Augmented Generation (RAG) * Embeddings and vector search * Semantic Kernel and AI workflow automation * AI integration into existing .NET applications 🔧 Already Have an Existing Application? You may not need a complete rewrite. I can work with your existing .NET, ASP.NET Core, Web API, Angular, React, and database codebases to understand the architecture, identify root causes, and implement targeted improvements. Whether you need to fix a critical bug, complete an unfinished module, integrate an external service, improve application security, or prepare your system for growth, my focus is on **solving the actual problem without introducing unnecessary complexity**. 🏗️ Architecture & Technical Leadership Beyond writing code, I can help you make better technical decisions. * Design maintainable application architecture * Build scalable APIs and backend services * Improve security, reliability, and performance * Review existing code and identify architectural risks * Plan modernization and cloud migration * Establish development standards and testing practices I can work independently or collaborate with your existing team, taking ownership of features and communicating progress clearly throughout the project. ## ⭐ Why Clients Work With Me * 10+ years of software development experience * Top Rated Plus freelancer on Upwork * 100% Job Success and 5.0 client rating * 73 completed jobs and 5.9K+ Upwork hours * Strong C#, ASP.NET Core, and Azure expertise * Experience across full-stack development, APIs, and integrations * Practical debugging and performance optimization skills * Focus on secure, clean, maintainable code * Reliable communication and long-term collaboration ## Let's Discuss Your Project If you need a **Senior .NET Developer, C# Developer, ASP.NET Core Developer, Azure Developer, API Developer, SaaS Developer, or AI Integration Engineer**, I’d be happy to help. Send me your requirements, existing technical challenges, or project goals. I’ll help you identify a practical solution and turn it into reliable, production-ready software. **Let's build something that works well today and scales for tomorrow.**