Oleksii O.

Fullstack Developer React, Next.js, Node.js, Typescript

Hello and thank you for visiting my profile! I’m Oleksii - a Senior Full-Stack Engineer with 5+ years of experience building production-ready, scalable web applications end to end using React, Next.js, Node.js, TypeScript, databases, and AI. I help startups and growing companies move from ideas or unstable systems to reliable, high-performance products with clean architecture, real backend logic, and thoughtful UX. What I usually help with • Building and maintaining full-stack applications (frontend, backend, APIs, data) • Designing clean application architecture and reusable components • Developing backend logic, API layers, and integrations • Improving performance and stability across the stack • Running A/B tests and product experiments based on real data • Integrating AI features (chat flows, smart suggestions, automation) • Building design-system-friendly UIs that scale with the product • Setting up CMS-driven content and data models without slowing the team A bit about where I’ve worked • Grammarly - worked on product UI components, performance refactoring, experiments, and CMS migrations in a large-scale production environment • Iceberg io - built AI-powered messaging features with OpenAI, rebuilt the landing experience, and implemented analytics and experimentation • ChainLink Education - developed a full SaaS platform end to end, including frontend, backend logic, data flow, and CMS-driven architecture Industries I’ve Delivered Solutions For: Fintech & Crypto: secure, high-performance full-stack development and database management Health & Wellness: mobile app developer for patient monitoring and wellness platforms Logistics & Supply Chain: automation, workflow, API integrations, real-time dashboard Education & E-Learning: interactive platforms with responsive web design and Nextjs Social Media & Marketing: scalable full stack software developer solutions with React.js front end My Approach to Projects: I focus on understanding business goals first, translating them into robust full stack web developer solutions with React.js, Node.js, and PostgreSQL / MongoDB databases. Every project is structured for performance, maintainability, and future scalability. I prioritize automation, clean code, and efficient workflow to save time and reduce risk for clients. Long-Term & Scalable Solutions: Many clients hire me as a full stack software engineer or software project manager for long-term collaboration. I provide guidance on architecture, Next.js frontends, React Node integrations, and mobile app development strategy. I also implement AI agents or OpenAI solutions when needed to enhance platform capabilities. Hands-On Technical Leadership: As a senior full stack developer react node and React full stack developer, I lead teams, review code, and ensure full stack development projects meet the highest standards. I integrate API, manage database structures, and maintain GitHub repositories for seamless collaboration. Why clients choose me: I combine React developer skills, Node.js backend expertise, and full full stack development knowledge to deliver results aligned with timelines and budgets. I provide long-term experience, from project planning to deployment, ensuring every workflow, database, and dashboard is optimized for performance. I’m comfortable owning features from idea to production, working closely with product, design, and backend teams, and making pragmatic technical decisions that move the product forward. Feel free to share the details of your project - I’ll review them and suggest the best way to achieve your goals efficiently.