Oleksii S.

Senior full-stack engineer (12+ yrs) and fractional CTO. I've shipped a healthcare SaaS used by millions, a loyalty platform that helped raise $5M, and cut one client's infra bill by 80%. I specialize in React.js, Next.js, Node.js, AWS, GCP, and AI-powered SaaS development, including advanced integrations with OpenAI, Anthropic, MCP servers, and modern agentic coding workflows. GPT-5 is now widely used in products like Cursor, Windsurf, GitHub Copilot, and Codex for agentic coding, while OpenAI Codex itself has evolved into a parallel agent workspace for cloud-based development. I actively use modern vibe coding and AI development tools such as Cursor, Cursor Composer, Windsurf Editor, OpenAI Codex, Claude Code, v0, Bolt, Lovable, Replit, GitHub Copilot, Devin, Tabnine, Qodo, Windsurf, Trae, and other AI-first builders to speed up delivery, reduce repetitive work, and improve code quality. Cursor has introduced Composer and a multi-agent interface, Windsurf positions itself as an AI-native IDE, and Claude Code now supports agent teams that can work in parallel on codebase tasks. I work with advanced models including GPT-5, Claude Sonnet 4.6, Claude Opus 4.6, and coding-optimized model workflows for architecture, debugging, refactoring, feature delivery, code review, and product acceleration. Claude Sonnet 4.6 is positioned by Anthropic as a major upgrade for coding, long-context reasoning, and agent planning, and Windsurf has also added fast coding-focused OpenAI model support. Achievements: 🎖️ Built an HRM loyalty platform that raised $5M 🚀 Developed a healthcare SaaS platform serving millions of users ✂️ Reduced infrastructure costs for a client by 80% 👨‍💻 My skill set: Frontend: React.js, Next.js, Remix, TypeScript, Redux, MobX, GraphQL, Apollo Client, MUI, Ant Design, SSR, SSG, Medusa.js Backend: Node.js, NestJS, Express, Firebase, AWS Amplify, MongoDB, PostgreSQL, MySQL, Redis, TypeORM, Hasura DevOps / Cloud: AWS, GCP, DigitalOcean, Vercel, Firebase, EC2, ECS, Kubernetes, CI/CD pipelines, self-hosted infrastructure Headless CMS: Contentful, Strapi, Sanity AI / Architecture / Performance: OpenAI, ChatGPT, Codex, Anthropic Claude, MCP servers, AI agent workflows, page speed optimization, Lighthouse, PageSpeed Insights, Python, Django, RabbitMQ, Kafka, Redis, microservices, micro-frontends, and database optimization 🧑 Shortly about me: • 12+ years of web development experience • 5+ years in team leadership and management roles • Strong product thinking from MVP and POC to scalable production systems • Deep experience improving existing products, architecture, security, performance, and revenue outcomes • Passion for building clean, efficient, visually polished interfaces and robust backend systems Key strengths: 💪 Strong expertise in Next.js, React.js, NestJS, and modern full stack architecture 💪 Hands-on experience with AI-assisted and agentic development workflows 💪 Excellent communication, ownership, and business understanding 💪 Ability to move fast with modern AI tools while keeping code maintainable 💪 Flexible, proactive, and focused on practical results 💪 Constantly learning and adopting the newest high-impact tools and workflows 📩🚀 Ready to elevate your project with modern full stack engineering and AI-accelerated development? Send me a direct message or invite me to your project, and let’s build something exceptional together.