Fedir Kopakov

Principal Full-Stack JavaScript Engineer and AI Product Developer with 13+ years of experience building SaaS products, startup MVPs, AI-powered applications, internal business platforms, and custom software for startups, SMBs, and funded companies. Delivered 200+ projects through Upwork and direct client relationships, combining hands-on engineering with product ownership, technical leadership, and fractional CTO work.

- Built products end-to-end from idea and MVP through production, covering architecture, UX, development, AI integrations, third-party APIs, and deployment.

- Built and integrated AI-powered product features using OpenAI, Anthropic, and Gemini APIs, LLMs, AI agents, tool calling, RAG, MCP, and AI workflow automation.

- Designed AI-enabled workflows and business automations using n8n, Make.com, webhooks, REST APIs, OAuth, and integrations with CRM, payments, communication, and productivity platforms.

- Designed and developed scalable SaaS platforms, MVPs, dashboards, and business applications using React, Next.js, TypeScript, Node.js, and modern cloud technologies.

- Worked directly with founders and business owners to turn business ideas into technical solutions, define MVP scope, make architecture decisions, and ship production software.

- Served as a fractional CTO / technical co-founder for startups, taking ownership of architecture, technology strategy, engineering execution, and product decisions.

- Managed small engineering teams and collaborated with Product, Design, Marketing, and other cross-functional roles.

- Handled technical sales, discovery, estimation, project planning, and client acquisition, including building long-term direct client relationships.

- Consistently ranked in the Top 0.5% of freelancers on Upwork with a track record of reliable, high-quality delivery.

Primary long-term freelance engagement throughout my career, including periods between other roles.

Principal Full-Stack JavaScript Engineer leading development of strategic product line using React, Node.js, and TypeScript. Acted as technical lead, product designer, and fractional CTO in cross-functional capacity.

- Architected and implemented scalable microservices architecture with React frontend and Node.js backend systems.

- Collaborated directly with VP of Design and C-level executives to shape user experience and product strategy.

- Led technical scoping, UX design, sprint planning, and agile delivery in enterprise environment with startup-like agility.

- Worked closely with DevOps teams on CI/CD pipelines, cloud infrastructure, and deployment automation.

- Mentored junior developers through code reviews, technical coaching, and best practices implementation.

- Delivered complex features including API integrations, data migrations, and performance optimization.

Senior Frontend Developer contributing to enterprise-level frontend systems using React, TypeScript, and modern web technologies. Key contributor in 100+ person engineering team, trusted with critical infrastructure development.

- Developed complex React components and scalable frontend architecture for enterprise SaaS applications.

- Maintained and evolved core frontend codebase using modern JavaScript frameworks and best practices.

- Collaborated with cross-functional teams to meet accessibility standards, security compliance, and performance requirements.

- Worked independently with minimal supervision while consistently meeting sprint deadlines and quality standards.

- Contributed to core products during high-growth phase using Agile methodologies and modern development workflows.

- Thentia raised over $59M in funding and is valued at around $100M now. I played a key role in the development of nearly all of their current revenue-generating products, and I was solely responsible for the company's main website and blog.