Denys Chepiha
Building products from 0 to 1 - React, Next.js, Node.js, NestJS, AI
CTO, Technical Founder & Senior Fullstack Engineer with 10+ years of experience building scalable systems and leading engineering teams.
My journey in tech goes beyond code - I've founded and co-founded products, led engineering teams, and helped companies scale from idea to production. Starting from HTML/CSS fundamentals, I've grown into a technical leader who designs complex ecosystems that perform under high loads. Today, I live and work in Austria, focusing on products that don't just work but deliver real value to businesses and users.
My Philosophy: Moving Only Forward
I am deeply convinced that in our industry, standing still is equivalent to resigning from professionalism. My approach is based on four pillars:
Constant Learning & Adaptability
I don't just follow the market - I actively implement new technologies. My current stack includes React 18 (Concurrent, Suspense), Next.js with App Router architecture, and TypeScript. Currently, I am diving deep into Rust for systems programming, studying cryptography and distributed systems, and integrating AI and LLM solutions (RAG pipelines, vector search) into modern applications.
Mentorship as a Mission
Training young specialists is my way of giving back to the community. I have successfully mentored Junior and Middle developers at companies like RocketHash, RMG Media, and English Dom. For me, it is important not just to review code, but to pass on a culture of writing high-quality, maintainable software.
Architectural Maturity
I specialize in modernizing complex legacy systems. My experience includes successfully applying the Strangler Pattern to safely migrate massive monoliths to modern Next.js foundations without halting business processes. I excel at building UI kits from scratch, implementing reliable state management strategies (Zustand, Redux Toolkit, XState), and ensuring frontend security (XSS prevention).
Fullstack Vision
While possessing deep expertise in Frontend, I am equally comfortable in Backend development with Node.js (NestJS, Express) and Python (Django, FastAPI). This allows me to view the product as a whole, design efficient APIs (REST, GraphQL, WebSockets), and optimize performance at every level - from the database (PostgreSQL, MongoDB) to the final frame rendered in the browser.
How I Can Add Value
Currently, I am open to new challenges and offer my expertise in the following areas:
High-Complexity Freelance Projects
Creating turnkey platforms - from initial architecture to cloud deployment.
Consulting & Auditing
Web Vitals performance analysis, frontend security audits, and developing migration strategies from legacy technologies.
Corporate Training & Mentoring
Helping your team adopt React/Next.js best practices, setting up CI/CD pipelines, and elevating the culture of code reviews.
I don't just write code. As a CTO, technical co-founder, or senior engineer - I build reliable products for your business growth, backed by 10+ years of experience, international certifications from Meta and IBM, and a track record of shipping at scale.
I'm ready to discuss how my technical leadership and engineering expertise can accelerate your next ambitious project.
Technical Skills
10+ years of hands-on experience across the full stack
Frontend
State & Data
Backend
Databases
AI & Infrastructure
Experience
10+ years of building products at scale
Languages
Education
Dnipro State Technical University
Computer Science & Information Technology
Dnipro, Ukraine · 2010–2014
Certifications
Meta Front-End Developer
Meta (Coursera) · 2023
Meta React Native
Meta (Coursera) · 2023
IBM Back-End JS Developer
IBM (Coursera) · 2022
IBM Full-Stack JS Developer
IBM (Coursera) · 2022