Krupal S.

Senior Full-Stack Product Engineer (React, Next.js, Node.js & AI SaaS)

I am a Top Rated Plus Senior Full-Stack Product Engineer with 8+ years of experience, $300K+ earned, and 14K+ hours delivered on Upwork. I build and improve SaaS products using React, Next.js, TypeScript, Node.js, and NestJS, and I help teams add practical AI features to real business workflows. I usually work with founders, product managers, designers, and engineering teams who need someone to do more than complete assigned tickets. I understand how the product works, how customers use it, and what needs to be solved first. From there, I can own a feature or product phase from planning and architecture through development, testing, and release. My experience includes customer and admin dashboards, multi-tenant SaaS platforms, CRM and ERP workflows, subscription and Stripe payment systems, user onboarding, roles and permissions, reporting, data visualization, file management, third-party integrations, and workflow-heavy business applications. On the frontend, I work mainly with React, Next.js, TypeScript, Redux, Tailwind CSS, and modern component libraries. I build responsive interfaces, complex forms, dashboards, reusable components, and data-heavy screens, while keeping performance and usability in mind. On the backend, I use Node.js, NestJS, Express.js, PostgreSQL, MongoDB, MySQL, Firebase, REST APIs, and GraphQL. I handle authentication, database design, business logic, integrations, background jobs, logging, and the structure needed to keep a growing product maintainable. I also help businesses improve their AI readiness and add useful AI features to existing products. This may include OpenAI-powered assistants, AI chatbots, document parsing, summarization, intelligent search, recommendations, content generation, workflow automation, and internal AI tools. My focus is not just connecting an AI model. I make sure the AI feature works properly with the product interface, backend, database, APIs, user permissions, and real workflow. I’m also comfortable taking over existing products that need new features, performance improvements, code cleanup, stronger architecture, better UX, or clearer technical ownership. I can work as a dedicated full-time or part-time engineer for a long-term product, or take ownership of a fixed-scope feature, MVP, integration, or development phase. I communicate clearly, raise risks early, and keep progress visible throughout the engagement. If you are building a SaaS product, improving an existing React or Node.js application, or planning to add AI to your platform, send me a short message about what you are building and where the product currently stands. I’ll review it and suggest the most practical way to move forward.