# 🚀 Senior .NET (ASP.NET Core) | React | React Native SaaS & Full-Stack Engineer I help companies build and scale **modern SaaS platforms, web applications, and mobile apps** using **.NET (ASP.NET Core), React, and React Native**. With 16+ years of experience in building production systems, I specialize in designing **scalable backend architectures, responsive frontends, and cross-platform mobile applications** that are maintainable, secure, and performance-driven. My focus is not just writing code — but building systems that are stable, scalable, and ready for real users. --- # 💡 What I Can Help You Build ### 🧠 SaaS & Web Applications * Full-stack SaaS platforms using .NET + React * Admin dashboards and business applications * Multi-tenant architectures and scalable backend systems ### ⚙️ Backend Engineering (.NET) * ASP.NET Core Web APIs and microservices * Clean architecture & domain-driven design * SQL Server / PostgreSQL database design and optimization * Authentication systems (JWT, OAuth2, Identity Server concepts) ### 🎨 Frontend Development (React) * React.js applications with TypeScript * Redux / Context API state management * Responsive UI development and component architecture * Integration with REST APIs and backend systems ### 📱 Mobile Development (React Native) * Cross-platform iOS & Android applications * API integration and offline support * Mobile UI/UX implementation * App performance optimization ### ☁️ Cloud & Deployment * Azure App Services and CI/CD pipelines * AWS deployment basics * Docker-based deployment setups (if required) ### 🔗 System Integration * Third-party API integrations (payments, authentication, business tools) * RESTful API design and integration strategies * Secure authentication and authorization flows ### 🔄 Legacy System Modernization * Migrating legacy .NET systems into modern .NET Core + React architecture * Improving performance, maintainability, and scalability of existing systems --- # 🏆 Why Clients Work With Me ✔ Strong expertise in building end-to-end full-stack systems ✔ Focus on scalable, production-ready architecture (not just prototypes) ✔ Experience modernizing and improving complex enterprise applications ✔ Ability to work across backend, frontend, and mobile seamlessly ✔ Clear communication and reliable long-term collaboration --- # 📊 Experience Highlights * 16+ years in enterprise and SaaS development * Delivered multiple full-stack applications from scratch to production * Experience handling large-scale business systems and integrations * Strong focus on performance optimization and clean architecture principles --- # 🌟 Recognition * Employee of the Year (2014) * Star Performer (2012, 2013) --- # 📩 Let’s Build Something Scalable If you're building a **SaaS product, modern web application, or mobile app using .NET and React**, I can help you design and develop it from architecture to deployment. Send me a message — I’ll review your idea and suggest the best technical approach before you hire anyone. How clients usually find me: Full stack .NET freelancer | hire ASP.NET Core developer | C# freelance programmer | experienced .NET Core API developer | enterprise ASP.NET freelancer | scalable ASP.NET Core solutions developer | full stack ASP.NET + Angular freelancer | ASP.NET + Vue.js developer for hire | remote full stack .NET developer India | affordable ASP.NET Core freelancer | top-rated .NET freelancer Upwork | ASP.NET MVC freelance developer | .NET SQL Server troubleshooting expert | cloud ASP.NET Core developer Azure | hire .NET API + AWS integration freelancer | Xamarin & MAUI cross-platform app developer | WPF/UWP MVVM freelance expert | ASP.NET Core migration freelancer | VB6.0 to .NET modernization freelancer | classic ASP to ASP.NET Core migration expert | legacy .NET maintenance & upgrade developer | .NET performance optimization freelancer | hire full stack C# web developer | ASP.NET bug fixing freelancer | .NET Core microservices developer | FHIR | QuickBooks/Xero/Sage integration ASP.NET freelancer | Twilio API + ASP.NET Core freelancer | Azure DevOps CI/CD .NET Core freelancer | enterprise SaaS .NET Core freelancer | ASP.NET Core + Bootstrap full stack developer | Angular 17 + .NET Core freelance expert | best ASP.NET full stack freelancer for hire | ASP.NET freelancer USA | hire remote .NET developer in UK | offshore ASP.NET Core developer Dubai | nearshore .NET full stack developer | hire ASP.NET Core + SQL Server expert | cloud-ready ASP.NET Core app developer | .NET Core REST API freelancer | experienced enterprise ASP.NET consultant | full stack ASP.NET Core freelance developer for scalable apps

I help engineering firms, manufacturers, and businesses automate complex workflows through software development, CAD automation, and AI-powered systems. Unlike most developers, I bring 15+ years of professional Civil Engineering experience combined with deep software development expertise. I understand drawings, engineering standards, design workflows, technical documentation, and the operational realities behind engineering projects. My work focuses on delivering production-ready solutions that save time, reduce errors, and automate repetitive processes. What I Do CAD & Engineering Automation • AutoLISP / Visual LISP Development • AutoCAD & ZWCAD Customization • VBA Automation • Drawing Cleanup & Standardization • Block & Attribute Automation • Batch Processing Tools • CAD Standards Enforcement • Legacy Script Debugging & Modernization • Engineering Workflow Automation • AI-Assisted Drafting Systems Software Development • Python Development • JavaScript / TypeScript • React, Node.js, Express, MongoDB (MERN) • REST API Development & Integration • Desktop & Web Applications • Database Design • Data Processing & Automation • Business Process Automation • Custom Internal Tools • Performance Optimization Systems Programming • Compiler Development • Interpreter Development • Language Processing Tools • Parsing & Code Analysis • Algorithm Design & Optimization • Technical Problem Solving AI & Agentic Systems • Claude API Integration • OpenAI API Integration • Claude Code • OpenAI Codex • Custom MCP Servers • Custom Skills Development • Retrieval-Augmented Generation (RAG) • Agentic Workflows • n8n Automation • AI Application Modernization • Multi-Agent Systems Recent Project Types • AutoCAD automation tools that reduce hours of manual drafting work to minutes • Custom engineering workflow systems • Compiler and interpreter implementations • AI-powered engineering assistants • Document and file processing automation • Business workflow automation platforms • Custom web applications and internal tools • CAD standards enforcement systems • Data extraction and transformation pipelines • LLM-powered applications using modern AI stacks Why Clients Hire Me • 15+ years of real engineering experience • Strong software engineering fundamentals • Ability to understand complex technical domains quickly • Production-focused solutions, not demos • Clear communication and reliable delivery • Long-term maintainable code • Available 30+ hours per week

Focused on creating and delivering stable, thoroughly tested and high performance solutions from simple to super complex challenges. I have top knowledge and experience in a variety of languages and frameworks including Python, C#, VBA, Django, React and Flutter, and employ modern industry standard tools and bleeding technologies to arrive to solutions. Also focused on building great business intelligence solutions using Powerbi and SQL. I'm very reliable, work very fast and am driven to ensure you get maximum value from my services.

Excellence Without the Expense! I'm Dejan! I've been programming since 2002 and am also a certified railway engineer. I'm passionate about data management, process automation, and simplifying things. I excel at understanding client needs, setting clear goals, bringing fresh ideas, and delivering beyond expectations. Once I'm on a project, I ensure it's done right and to your satisfaction. 🟢What Clients Say About Me: - Proficient Expertise: Trusted in MS SQL and .NET. - Reliable Delivery: Projects delivered punctually. - Clear Communicator: Appreciated for timely and effective communication. - Client-Centric Approach: Tailoring solutions for unique client needs. - Always Accessible: Responsive, irrespective of time zones. - Quality Deliverables: Consistent excellence in output. - Quick Problem Solver: Swift in addressing challenges. - Above & Beyond: Going the extra mile for success. - Genuine Dedication: Prioritizing project excellence over financial gains. - Highly Endorsed: Frequently recommended by satisfied clients. I am Serbia based programmer with an extensive background in a variety of technologies. I speak English, Serbian and have all-time support in Vietnamese. 🟢My Technical Proficiency: - Desktop Development: Expert in C#, Visual Basic .Net, and Office Add-Ins. - Web Development: Skilled in PHP, HTML, JavaScript, CSS. - Database Mastery: Proficient in MSSQL, MySQL - from development to administration. - SEO: Unique strategies for optimizing search engine results. - Data Processing: Specializing in web scraping, parsing, data extraction, and automation. - Certifications: Proud Microsoft Certified Professional (MCP). I also offer VBA, Python, Classic ASP, VB6 services, and tasks like DNS setups, backups, web hosting administration, and more. 🕘Reach out between 9 AM and 6 PM CEDT (before 11 AM PDT | before 2 PM EDT | after 6 PM AEDT) and remember, good communication is key to everything! 🌍 Please search for me online: dejan dozet programmer Best Regards, Dejan Dozet

I’m a senior Excel VBA developer with 29 years of corporate-level experience automating spreadsheet processes, enhancing productivity, and modernizing legacy applications. My clients have included MassMutual, The Hartford, Pratt & Whitney, Connecticut Children’s Medical Center, CVS/Health, and more than 85 Upwork clients. For Cornerstone Real Estate Advisers (a MassMutual subsidiary), I developed a suite of proprietary budgeting tools that saved the firm over $1 million in commercial software licensing fees. The suite of asset-type-customized workbooks ran successfully for two decades and was widely preferred to commercial software alternatives across a user base of 100+ property management companies in the U.S. and Canada. Excel VBA is my specialty. I build and code robust automation solutions, eliminate time-consuming manual tasks, and stabilize unstable or error-laden workbooks. I also integrate Excel with Word, Outlook, and other MS Office applications for data-driven document generation and communication workflows. With advanced writing skills and an editor’s keen eye, I deliver top-shelf documentation. I write clean VBA code that is easy to follow, maintain, and troubleshoot, using a style refined over nearly three decades—far more readable, efficient, and maintainable than typical auto-generated macro code. I'm experienced collaborating with professionals in finance, accounting, engineering, and actuarial science—delivering tools that streamline operations, enhance decision-making, and stand the test of time. I favor a structured, incremental development process—guided by clear communication and steady progress toward the right solution. My goal isn’t just to deliver working code—it’s to create lasting value, delivered clearly, with precision and purpose.

I am an experienced .NET Developer with over 13 years of expertise in designing, developing, and modernizing enterprise applications. My core skills include VB6, VB.NET, C#, WPF, WCF, Web API, and Crystal Reports, along with strong database experience in MS-SQL, MySQL, and MS-Access. I have a proven track record in: 1- Maintaining and managing big legacy applications primarily written using VB6/VB.NET/C#. 2- Application Migration – Successfully modernizing legacy VB6 applications to .NET platforms. 3- Database Modernization – Migrating MS-Access databases to SQL Server with optimized structures. 4- Reporting Solutions – Advanced knowledge of Seagate and SAP Crystal Reports with diverse data sources. 5- API & Protocols – Implementation of TCP, UDP, and HTTP APIs for seamless integrations o Socket programming. 6- Enterprise Applications – Extensive experience delivering POS, CRM, and ERP solutions for global clients. With a strong background in desktop and Windows applications, I bring both technical expertise and problem-solving skills to help organizations modernize and scale their business-critical software. I am confident that my experience in migration, integration, and enterprise application development will add value to your team

I’m a senior software engineer with 13+ years of professional experience building scalable, data-driven applications, robust backend services, and modern API systems for clients worldwide. I help businesses transform ideas into reliable software that performs both today and long into the future. 💡 What I do best • Build API-first backends & microservices that deliver reliable integrations • Architect systems using clean, maintainable layered patterns • Modernize legacy applications while preserving business value • Integrate external systems, services, and third-party platforms • Support end-to-end development from design to delivery 🚀 Technical Strengths • CSharp & VB core development • API development (RESTful APIs, JSON workflows, async service patterns) • Modern web & backend frameworks • SQL Server design, optimization, and advanced queries • Enterprise tooling (UI frameworks, dashboards, reporting systems) • CI/CD practices, testing, and deployment pipelines 🌍 What Clients Hire Me For ✔ Building APIs and backend modules that scale ✔ Extending or rewriting legacy applications ✔ Delivering robust Windows & Web solutions ✔ Integrating systems like maps, analytics, payments, and data services ✔ Ensuring quality with strong architecture and testing practices 📈 Why Work With Me • I approach every project with clarity, ownership, and long-term stability. • I communicate clearly, meet commitments, and deliver solutions that align with your business goals. • Flexible remote support—small enhancements or full module builds. If you want a dependable engineer who delivers clean code, modern architecture, and long-lasting software quality, let’s discuss your project and how I can help you succeed. 🚀

🚀 I automate repetitive data work so humans don’t have to I strongly believe that people shouldn’t waste time on work that a computer can do better. Over 90% of data extraction, reporting, and routine Excel tasks can — and should — be automated. I help businesses eliminate manual work, reduce errors, and save time by building reliable automation solutions. 💼 My background - 6+ years of experience in process automation - Strong background in Excel VBA, data processing, and reporting - Previous experience in a large financial organization, where I automated routine workflows for teams - Long-term freelancer with repeat clients I started programming early and have always enjoyed turning “boring manual work” into one-click solutions. Watching a process run automatically — accurately and consistently — is still the best part of my job. 🛠 What I can help you with - Excel automation (VBA macros, dynamic reports) - Data extraction and transformation - Automated reporting and dashboards - Complex formulas, pivot tables, conditional formatting - Cleaning, validating, and structuring data - User-friendly tools with clear documentation If you have data that needs to be collected, processed, transformed, or reported — I can automate it. ✅ How I work - Clean, maintainable solutions - Friendly interfaces — not “black box” macros - Clear documentation so your solution can be extended later - Honest communication and realistic estimates - I only take projects I am 100% sure I can deliver - I respect my clients’ time, meet deadlines, and provide follow-up support when needed. Let’s discuss your problem — I’ll help you find the most efficient solution.

I help SaaS companies and enterprises modernize their infrastructure and ship faster — by combining senior .NET architecture with cloud-native DevOps, Python data pipelines, and AI/ML integrations on Azure and AWS. What I deliver: 🔹 .NET + Full Stack — C#, .NET 8, TypeScript, React, Node.js, Angular 🔹 Azure — Functions, App Services, Azure OpenAI, Azure DevOps, AKS, CosmosDB, Blob, Cognitive Services 🔹 AWS — EC2, S3, Lambda, ECS, CloudWatch, API Gateway 🔹 MLOps & AI — Python ML pipelines, Azure ML, Google Gemini API, model deployment, Azure Data Factory, Delta Lake, Microsoft Fabric 🔹 DevOps & CI/CD — Docker, Kubernetes, GitHub Actions, Jenkins, Terraform (IaC), Datadog, Grafana, Prometheus, ELK Stack 🔹 Data Engineering — ETL pipelines, MS SQL, PostgreSQL, MongoDB, CosmosDB, performance tuning, data warehousing 🔹 VBA & Excel Automation — VSTO add-ins, Office Online, macro development 🔹 Integrations — QuickBooks, Stripe, Twilio, SendGrid, Google APIs With 17+ years of hands-on experience, $200K+ earned, and 150+ completed projects, I understand what enterprise clients need: clean architecture, on-time delivery, and zero surprises. Currently available for Azure/AWS migrations, .NET modernization (to .NET 8/9), MLOps pipelines, and DevOps automation projects. Let’s Talk! ------------ If you're ready to streamline your operations and achieve measurable results, let’s discuss your project today. I look forward to working with you!

THANK YOU FOR VISITING MY PROFILE My name's Cong. I've been a VBA developer for 8 years specializing in data analysis and visualization, user interface, and applications using Excel VBA. I've been on Upwork for almost 4 years with 100% Job success and Top rated. Here's what I bring to the table: -Advanced Excel Formulas -Excel Pivot Tables -Data Analysis in Excel - Excel Dashboard Creation - Excel Macros/VBA (Visual Basic for Applications) - Excel Charts and Graphs - Excel Templates Development - Excel Data Visualization - Excel Automation - Excel Data Cleansing and Formatting - Excel Functions Mastery (e.g., VLOOKUP, INDEX/MATCH, SUMIFS, COUNTIFS) - Excel Conditional Formatting - Excel Spreadsheet Design and Organization - Excel Data Validation - Excel Reporting - Excel automation bug solving I used to work as an automation engineer in Japan for 3 years so I also can translate English <> Japanese. - Besides that, I am also a mechatronic engineer so I can do Electrical design and PLC/HMI programming (especially Mitsubishi PLC/TP) -I can use English and Japanese fluently (TOEIC 700 and JLPT N2) - I am a person who is always willing to listen and learn so please get in touch with me to accomplish your goals! Thank you!