Yaroslav K.

Full Stack React Node.js Nest.js Next.js Express.js JavaScript TypeScript Redux Open AI integration SAAS Material UI Tailwind CSS styled-components Firebase Supabase Mongo DB PostgreSQL Redis Open AI API GraphQL LLM Integrations WebSockets AWS Docker Stripe I help founders and product teams build new SaaS applications, integrate AI/LLM features into existing products, and take AI-generated or prototype applications to production. I use Claude Code and GitHub Copilot daily as part of my development workflow, while keeping architecture, code quality, security, testing, and production decisions under engineering control. $100K+ earned | Top Rated Plus | 100% Job Success | 4,700+ Upwork hours What we build: AI & SaaS Products AI-powered SaaS, AI agents, RAG systems, copilots, automation, multi-tenant platforms, subscription products. Web Platforms Marketplaces, booking systems, real estate platforms, FinTech, healthcare, EdTech, social and community products. Mobile Applications Cross-platform mobile products with React Native and Flutter, including API-heavy applications, marketplaces, booking, social and SaaS products. Product Development & Modernization New product development, MVPs, existing platform development, architecture modernization, integrations, performance improvements, and production hardening. Core engineering stack: Frontend: React, Next.js, TypeScript, JavaScript, Tailwind CSS, shadcn/ui, Material UI, TanStack Query Backend: Node.js, NestJS, Express.js, REST API, GraphQL, WebSockets Database & Backend Services: PostgreSQL, Supabase, Firebase, MongoDB, Redis AI: OpenAI API, Anthropic Claude, LLM integrations, AI agents, RAG, embeddings, vector databases, Pinecone Cloud & DevOps: AWS, Docker, CI/CD Integrations: Stripe, Twilio, SendGrid, third-party APIs, OpenAI API Mobile: React Native, Expo, Flutter Typical projects I can help with: • Take an AI-generated, Lovable, Bolt, Replit, or prototype application and make it production-ready • Build a SaaS or web application from Figma or an existing specification • Take an AI-generated, Lovable, Bolt, Replit, or prototype application and make it production-ready • Add AI agents, RAG, LLM workflows, copilots, or OpenAI/Claude integrations to an existing product • Build or extend React / Next.js frontends and Node.js / NestJS backends • Build authentication, subscriptions, payments, dashboards, admin panels, and multi-tenant architecture • Integrate Stripe, external APIs, CRMs, communication services, and other third-party systems • Review an existing codebase and fix architecture, performance, security, or scalability issues • Continue development of an existing SaaS product without rebuilding everything from scratch Working with me and INCODE Group I’m part of INCODE Group, a software development company with 10+ years of experience building web, mobile, SaaS, and AI-powered products. This means I can work directly on the engineering side of your project, while also bringing in additional INCODE specialists when the product requires a larger team: frontend and backend engineers, Flutter / React Native developers, QA, DevOps, UI/UX designers, or AI engineers. We can support both focused development tasks and complete product delivery, from technical discovery and architecture to development, testing, deployment, and ongoing product development. If you already have a product, codebase, Figma, prototype, or technical specification, send it over. I can review it from the engineering side and discuss the best way to move it forward. Track record • $100K+ earned on Upwork with 100% Job Success and Top Rated Plus status • 4,700+ hours and 27 completed Upwork projects • 10+ years of software development and product delivery experience • Experience building and scaling SaaS, AI, marketplace, booking, real estate, healthcare, EdTech, and social products • Long-term experience taking products from early MVP and prototype stages to production and ongoing development • Hands-on work with complex integrations, payments, subscriptions, real-time functionality, multi-role systems, and cloud infrastructure I’m a good fit if you need someone who can: • Own the technical side instead of working only from isolated tickets • Join an existing codebase and understand it before proposing a rewrite • Turn an AI-generated prototype into maintainable production software • Work directly with founders, CTOs, and product teams on technical decisions • Start with one senior engineer and scale into a larger INCODE team when the project requires it