I'm a Senior Full-Stack & AI Engineer with 15+ years of experience building scalable web, mobile, and AI-powered applications. I help startups and enterprises turn ideas into production-ready products using modern frontend frameworks, cloud infrastructure, and cutting-edge AI technologies. My development lifecycle is hyper-optimized. I build intelligent applications—utilizing the MERN stack and Next.js—and deploy them seamlessly on modern infrastructure like Vercel. More importantly, my workflow is driven by advanced AI: I leverage Claude, Antigravity, Cursor, and custom-built IDE agents to write, refactor, and debug code at an unprecedented speed. Whether you need a sophisticated LLM integration (OpenAI, Anthropic, LangChain) or a high-performance web app delivered ahead of schedule, I bring enterprise-level project management and engineering to your team. I have successfully delivered 50+ projects, including SaaS platforms, AI applications, mobile apps, enterprise dashboards, and high-scale APIs. My expertise covers the entire product lifecycle — from architecture and development to deployment, scaling, and automation. Core Expertise Frontend Development Modern, fast, and scalable user interfaces. HTML5, CSS3, Tailwind JavaScript (ESNext), TypeScript React, Next.js, Redux Angular, Angular Universal, Angular Material Vue.js, Vuex Progressive Web Apps (PWA) Mobile App Development Hybrid cross-platform mobile apps. React Native Flutter Ionic Mobile-first UI architecture App Store & Play Store deployment Backend Development High-performance APIs and scalable backend systems. Node.js Express.js NestJS Sails.js LoopBack Microservices architecture REST APIs & GraphQL Databases Designing scalable and optimized data systems. MongoDB MySQL / PostgreSQL DynamoDB Redis Firebase / Firestore FaunaDB Cloud & DevOps Reliable cloud infrastructure and automated deployments. AWS Google Cloud Platform (GCP) Microsoft Azure Docker & containerized deployments CI/CD pipelines Serverless architecture Auto-scaling infrastructure Kubernetes (basic/optional if you want) AI / Machine Learning Expertise I build AI-powered applications, automation systems, and intelligent tools using modern LLM and ML platforms. Generative AI & LLMs Google Gemini Models Vertex AI OpenAI APIs AI chatbots AI assistants RAG systems (Retrieval Augmented Generation) AI workflow automation Machine Learning Platforms Microsoft Azure AI Azure Bot Services Face API Cognitive Search Form Recognizer Azure Machine Learning Video Indexer AWS AI Services Amazon Rekognition AI-powered image analysis Google AI Vertex AI Gemini models AI model deployment What I Can Do For You ✔ Full-Stack Web Application Development ✔ AI-powered SaaS Products ✔ Mobile Apps (React Native / Flutter) ✔ API Development & Integration ✔ Cloud Infrastructure Setup ✔ DevOps Automation (CI/CD) ✔ Scalable Backend Architecture ✔ AI Chatbots & Intelligent Systems ✔ Performance Optimization & Scaling Types of Projects I Build SaaS platforms AI applications Startup MVPs Enterprise dashboards E-commerce platforms Progressive Web Apps Mobile apps Automation systems API platforms

🚀 Full-Stack Developer | Web, Mobile & API Solutions I help businesses build scalable web and mobile applications using modern frameworks like React.js, Next.js, React Native, Node.js, Express.js, FastAPI, and Django. With expertise in JavaScript, TypeScript, and Python, I deliver high-performance solutions tailored to your needs. 🔹 Backend & APIs: Node.js, Express, FastAPI, Django, REST, GraphQL, JWT/Auth, Microservices, SwaggerUI 🔹 Frontend & UI: React.js, Next.js, React Native, GSAP, Lenis animations, SEO-friendly web apps 🔹 Databases: PostgreSQL, MongoDB, Prisma, Mongoose, ORM, SQL/DBMS concepts 🔹 Cloud & DevOps: AWS, Docker, Linux, Nginx, CI/CD pipelines 🔹 Software Practices: Software Design, Scalable Architecture, Secure Authentication, Testing 💡 I’ve worked with startups, SaaS products, and eCommerce businesses, helping them scale their apps and optimize performance. ✅ What you get: Clean, maintainable, and scalable code Fast & responsive UI/UX Secure authentication & API integration Reliable deployments with CI/CD Let’s bring your idea to life 🚀

✅ 100% Client Satisfaction | Proven Partner for Scalable Software Solutions With years of hands-on experience building reliable, scalable, and high-performance software for both startups and established enterprises, I bring a deep commitment to delivering solutions that truly make a difference. Whether you’re launching an MVP, scaling an existing platform, or tackling complex software challenges, I’m here to help you succeed with clean, maintainable code and clear communication every step of the way. 🚀 What I Bring to Your Project • 🔧 Smart solutions to complex business problems tailored for your specific goals • 📦 Clean, scalable, and maintainable code that follows best practices and design patterns • 📈 Strategic thinking and product-oriented development to drive real value • 🕐 Reliable availability and proactive communication • 💡 A forward-thinking mindset that evolves with the latest technologies 💻 Frontend Expertise • TypeScript, React, Next.js, JavaScript, HTML5, CSS3 • State Management: Redux, Zustand, React Query • UI Libraries: Tailwind CSS, ShadCN/UI, Material UI, Chakra UI, Sass • Seamless API integration 🛠 Backend Expertise • Node.js (Express.js, NestJS) • Python (Django, FastAPI) • Third-party Integrations: ChatGPT, Twilio, Firebase, Supabase • RESTful & GraphQL API development 📱 Mobile Development • Flutter (Dart), React Native – for high-quality cross-platform apps ⚙️ DevOps & Cloud • Docker, Kubernetes • CI/CD with Jenkins & GitHub Actions • Cloud Services: AWS, Vercel, DigitalOcean 🗄️ Database Management • Relational: PostgreSQL, MySQL, SQL • NoSQL: MongoDB, Firebase Realtime DB 📩 Let’s Talk If you’re looking for a developer who is not just a coder, but a strategic partner in your project’s success—let’s connect. I’m always ready to take your vision from idea to launch and beyond. Let’s build an amazing product together!

I'm a senior full-stack developer with over 15 years of experience building scalable and reliable web applications from the ground up. I specialize in backend architecture, API development, and complex front-end integrations. My technology stack covers: 🔹 Backend: Node.js (Express, NestJS), Python (Django, Flask, FastAPI), PHP (Symfony, Laravel, Yii2), REST & GraphQL APIs, WebSocket (Socket.io), Celery, RabbitMQ, JWT-based auth, Firebase Functions 🔹 Frontend: React (Redux), Tailwind CSS, TypeScript, Next.js, Vue.js, HTML5, SCSS, Webpack, Vite, responsive & RTL layouts 🔹 Databases: PostgreSQL, MySQL, MongoDB, SQLite, Elasticsearch, TypeORM 🔹 DevOps: Docker, Docker Compose, CI/CD pipelines (GitHub Actions, GitLab CI), Nginx, PM2, AWS (EC2, S3, RDS), DigitalOcean, Heroku, Vercel, cron jobs, monitoring/logging (Sentry, LogRocket) 🔹 Others: Stripe, PayPal, Coinbase Commerce, Google Maps API, OpenStreetMap, Firebase, Cloudinary, SendGrid, Mailgun, Excel/CSV parsers, role-based access control (RBAC), audit logs, data encryption (AES, TLS), GDPR tools (data export/deletion), multi-language & RTL support, performance profiling & optimization, API versioning In the past year, I’ve delivered a large AI-enhanced platform. This experience includes building content generation tools powered by OpenAI, smart recommendation engines, and automated data categorization systems. I have hands-on experience integrating with GPT-based APIs and building backend workflows around AI services. Focusing on high-impact work, I've also successfully delivered over 3 significant long-term projects over the last year, including a Real Estate referral platform, a Referee management system, and a Delivery management solution. My broader expertise also covers building SaaS platforms, ERPs, and complex marketplaces. I work well independently or as part of a distributed team and always prioritize clean, maintainable code and clear communication. 🔸 Fluent in English 🔸 Prefer video-on calls to build better connection 🔸 Committed to long-term, value-driven cooperation

I have strong expertise in MySQL, SQL Server, MongoDB, PostgreSQL, PHP, Laravel, Vue.js, Node.js, Linux, and ViciDial. With over 20 years of experience, I specialize in designing, developing, and delivering high-performance, scalable solutions, including complex call center systems and custom VoIP integrations.

I'm a Senior React/Nodejs developer with over 5 years of experience in building innovative web and mobile applications. Experienced in collaborating with diverse, global teams to develop robust and innovative solutions. 📣💬️ Contact a Top Rated developer and I will offer the best solutions for your project! 💯 What my clients say about me: ⭐️⭐️⭐️⭐️⭐️ “You did a great job. Thank you for the quality work on the database of our new application.” ⭐️⭐️⭐️⭐️⭐️“Serhiy did an outstanding job on our web app project. He integrated Stripe seamlessly, fixed complex frontend issues, and delivered a robust backend solution. Communication was clear and consistent, and he provided valuable suggestions throughout. The work was completed on time, with high-quality code.” 🖥 Languages: TypeScript, JavaScript, HTML 🔝Frontend: React, React Native, Redux, SASS, Bootstrap, Less, Next.Js, MaterialUI, Tailwind CSS, Styled Components, Rtk query, Redux Saga, Redux Toolkit, Redux Thunk, Socket.io, Retool, Strapi 🔙Backend: MongoDB, PostgreSQL, NodeJS, ExpressJS, NestJs, GraphQL, Websockets, Serverless, Jest, Lambda, DynamoDD, SES, API Getaway, S3, SNS ☁️Cloud: AWS, Google Cloud Platform, Heroku, Vercel ⚔️Tools: Git, Github, Bitbucket, Gitlab, Jira, Microsoft Teams, Slack, Trello, Agile Scrum, Kanban Let's work together! 10/11/2025 updated

I’m a Principal Full Stack Engineer and Software Architect with 15+ years of experience designing and scaling SaaS, AI, Fintech, Healthcare, and E-Commerce, and now evolving those platforms with AI-driven capabilities. I design architectures where LLMs, embeddings, and data pipelines work alongside robust APIs, enabling automation, insight generation, and conversational interfaces inside enterprise products. I’ve worked across the full company spectrum: • Startups that needed rapid MVPs, lean architectures, and fast iteration • Scaleups where performance, stability, and automation become critical • Enterprises with complex compliance, multi-team collaboration, and long-term architectural planning My Teck Stacks & Specializations: • Frontend: React, Next.js, TypeScript, Tailwind, Material UI • Backend: Node.js (Express, Nest.js), Python (FastAPI, Django), Java, C#, REST, GraphQL, WebSockets AI & Data: LLMs, RAG pipelines, embeddings, vector DBs, LangChain, LlamaIndex, ETL/ELT • Cloud & DevOps: AWS, Azure, GCP, Docker, Kubernetes, Terraform, CI/CD (GitHub Actions, Azure DevOps) • Databases: PostgreSQL, MySQL, MongoDB, Redis, DynamoDB • E-Commerce / CMS: Shopify, WooCommerce, WordPress (custom plugins, headless setups) I specialize in system and database architecture, designing platforms that handle complex business logic, high traffic, and real-time data at scale. I build distributed ecosystems using domain-driven design, microservices, and event-driven patterns, supported by resilient messaging workflows, serverless compute, and horizontally scalable APIs. From orchestrated services to autonomous event pipelines, and from optimized relational models in PostgreSQL/MySQL to high-throughput document and cache layers in MongoDB and Redis, I ensure every layer of the system is tuned for performance, reliability, and seamless growth. On the product side, I’ve built and optimized Shopify, WooCommerce, and custom WordPress solutions - integrating payments, automating operations, and improving conversions through smart architecture and automation. Clients value me for translating complex requirements into intuitive, high-performance applications while leading projects with transparency and efficiency. Every engagement is about long-term reliability. I ensure that what we build today continues to support tomorrow’s growth.

I am serving as a Full Stack developer and have worked on comprehensive applications for different market verticals in last 7 years. My core expertise has been delivering bespoke solutions that meet the client's requirements. Here's a quick brief about my technical skills: - MEAN/MERN Stack (Node.js, Express, Angular.JS, MongoDB, ReactJS). - RESTfull APIs and GraphQL. - Responsive Design. - Version Control - Git, SVN. - Photoshop, UI/UX, Graphics Designing. - Experience using third party APIs. - Developing jank free websites that load faster. I am capable of assisting my clients with entire development cycle starting from requirements gathering, application GUI, application front-end and back-end development. I have developed simple to complex web application using ReactJS, Angular, NodeJS, MongoDB, ExpressJS. As a full stack developer, am responsible for writing server-side web application logic and the front end part too. I develop back-end components, connect the application with the other (often third-party) web services, and integrate with the front end components of the application.

If you're looking to: • Build AI-powered SaaS applications or platforms • Develop GPT-powered chatbots, assistants, or LLM systems • Integrate APIs, CRMs, and third-party services • Implement RAG pipelines or intelligent document systems • Scale a full-stack product with clean architecture => I can help you go from idea → production-ready system. I build scalable AI-powered applications using .NET, Python, and modern frontend frameworks, combined with LLMs like OpenAI (GPT). My focus is not just writing code, I design and develop complete systems that handle real-world use cases, from AI features to backend architecture and integrations. 𝗪𝗵𝗮𝘁 𝗜 𝗰𝗮𝗻 𝗵𝗲𝗹𝗽 𝘆𝗼𝘂 𝘄𝗶𝘁𝗵: • AI chatbots & GPT-powered assistants (OpenAI, LLMs) • RAG systems (document processing, embeddings, semantic search) • Full-stack SaaS development (.NET, React, Angular) • API integrations across CRMs, SaaS tools, and databases • AI-powered features inside existing applications • Backend architecture, system design, and scalability • Automation and workflow systems 𝗧𝗲𝗰𝗵 𝘀𝘁𝗮𝗰𝗸: • Core: C#, .NET Core, Python, Node.js, JavaScript • AI: OpenAI (GPT), Azure OpenAI, LLMs, Semantic Kernel, LangChain, embeddings • AI Development: Claude Code, GitHub Copilot, Codex, Cursor, Windsurf, Manus, Antigravity • Backend: ASP.NET Web API, microservices, REST APIs, webhooks • Frontend: React.js, Angular, Next.js, TypeScript • Data: SQL Server, PostgreSQL, MongoDB, vector databases (Pinecone / Qdrant) • Cloud: Microsoft Azure (App Services, Functions), Docker, CI/CD • Integrations: APIs, CRM systems, SaaS platforms • Real-time & Payments: SignalR, Stripe, PayPal 𝗪𝗵𝗮𝘁 𝗽𝗿𝗼𝗯𝗹𝗲𝗺𝘀 𝗜'𝘃𝗲 𝘀𝗼𝗹𝘃𝗲𝗱: • AI Content Generation System (GPT + APIs) Extended an AI-driven visual/content generation platform with improved logic, API orchestration, and scalability. • Stripe Payment Integration (.NET + Angular) Integrated secure payment workflows across frontend and backend, ensuring reliable transactions and system stability. • Full-Stack Application Development (.NET + SQL + APIs) Built and enhanced scalable applications with clean architecture, optimized database design, and API-driven workflows. • AI Feature Integration (OpenAI / Azure OpenAI) Added GPT-powered functionality into existing platforms to enable intelligent automation and user interactions. • Real-Time System Features (SignalR + Backend APIs) Implemented real-time updates and communication layers for dynamic, user-facing applications. Let’s take a look at your product or idea and map out the best way to build it using AI, .NET, and scalable architecture.

Next.js | React.js & Node.js Architect: I transform your AI SaaS and MVP concept into a scalable, investor-ready product. Top Rated Plus developer with 8+ years of experience building production-grade web applications for funded startups, SaaS companies, and growing businesses across healthtech, fintech, edtech, and e-commerce. I don't just write code. I engineer systems that scale. Whether you need an AI-powered SaaS platform, a ChatGPT-integrated dashboard, or a full-stack MVP ready for launch in weeks, I deliver clean architecture, rapid execution, and clear communication from start to finish. What I Build For Clients Like You: 🚀 AI SaaS Platforms & MVPs End-to-end development of AI-powered web applications. OpenAI / ChatGPT API integration, custom AI chatbots, AI automation workflows (n8n), and complete SaaS MVPs built with Next.js and Node.js. I help founders go from idea to live product 40% faster. 💻 Full-Stack Web Applications Scalable, high-performance apps using Next.js, React.js, Node.js, Express.js, TypeScript, and Vue.js. Real-time features, complex dashboards, booking systems, ERP, and CRM solutions engineered for performance. 📱 Mobile Applications Cross-platform iOS and Android apps built with React Native and Flutter. Real-time messaging, live streaming, and seamless API integration with your web backend. 🔌 API Development & Integrations REST and GraphQL APIs. Stripe subscriptions and payment systems. PayPal, Google Maps, SMS gateways, shipping APIs, and third-party service integration built securely and documented clearly. ☁️ Cloud & Deployment AWS, Azure, Docker, CI/CD pipelines. I build for scale from day one so your infrastructure grows with your user base—not against it. Tech Stack I Work With Daily: Next.js React.js Node.js Express.js TypeScript JavaScript Laravel Vue.js React Native Flutter MongoDB PostgreSQL MySQL Supabase Firebase Python Redux Tailwind CSS Material UI GraphQL REST APIs Docker AWS Azure GitHub OpenAI API ChatGPT n8n Recent Results Delivered: 🔹 Built an AI-powered SaaS MVP for a healthtech startup, reducing time-to-market by 40% and securing their seed funding round. 🔹 Developed a real-time booking platform with Stripe payments, processing 10,000+ monthly transactions with 99.9% uptime. 🔹 Engineered a fintech dashboard using React and Node.js that improved data processing speed by 3x, handling millions of records in real time. What Clients Say: ⭐ "Great developer with strong expertise in React, Node.js, API integrations, and SaaS application development. Delivered high-quality work, communicated effectively, and handled Stripe and AI-related integrations smoothly. Highly recommended and would hire again." ⭐ "Excellent MERN Stack developer. Delivered a high-quality responsive web app with smooth API integration and strong performance. Communication was clear, work was delivered on time, and all requirements were met perfectly. I highly recommend her for full-stack web development." Frequently Asked Questions: Can you build my AI-powered SaaS product? Yes. This is my core specialty. I build complete AI SaaS platforms with ChatGPT/OpenAI integration, custom chatbots, and intelligent automation workflows. I've helped multiple startups launch AI products from zero to production. Do you develop MVPs for startups? Absolutely. I work with founders to define scope, prioritize features, and launch a fully functional MVP in weeks—not months. The architecture is always built to scale when you're ready. Can you integrate Stripe and payment systems? Yes. I've implemented Stripe subscriptions, one-time payments, invoicing, and recurring billing for multiple platforms handling thousands of transactions monthly. Do you provide ongoing support after launch? Yes. I offer maintenance, bug fixes, feature enhancements, and long-term technical partnership. Most of my clients stay with me for years. Are you available for long-term projects? Yes. I'm actively seeking long-term collaborations and am open to contract-to-hire arrangements. I focus on three things: clean code, clear communication, and solutions that create real business value. If you're looking for a Next.js Developer, Node.js Developer, AI SaaS Specialist, or MERN Stack Architect, send me an invitation and let's discuss your project this week. — Monika Next.js & Node.js Developer | AI SaaS & MVP Specialist | Top Rated Plus Keywords : Monika full stack developer on Upwork, MERN Stack, React Native Developer, Laravel, AI Solutions, Bubble, Mobile App Development, E-commerce Development, SaaS Applications, Web Development, Custom Websites, RESTful API, MongoDB, MySQL, PostgreSQL, Firebase, - Best Full stack developer on upwork - Hire best react developer upwork 2026 - Best Developer for AI Saas Platform & Mvp Development - Monika expert full stack developer on Upwork - Hire MERN Full Stack Developer Upwork - Monika Senior Backend Engineer (Node.js / TypeScript / AI) Upwork