Oleksii K.

I build and speed up React and Next.js products: SaaS dashboards, Stripe billing and data-heavy admin tools. On one platform, page loads got roughly 30% faster and traffic grew 12.8% month over month, to about 370K monthly visits. What I take on: - New products and MVPs, from stack choice and architecture to deployment (Next.js, Node.js, PostgreSQL, Vercel) - Django REST back ends with React front ends: APIs, Celery background jobs, Excel and PDF exports, reports - Slow or fragile code: front-end performance work, database query fixes, JavaScript to TypeScript migrations, step-by-step refactors that keep the app running - Stripe billing, subscriptions and pay-at-table payments - Real-time features: live video streaming with LiveKit and WebRTC, WebSockets - Data-heavy dashboards and admin tools: large tables, reports, complex forms, live updates - Ad-tech integrations: Google Ad Manager, DV360, Meta and TikTok APIs Work behind the claims: - 24Slides: moved the platform to Gatsby and TypeScript (average session length reached 1m 33s), led the SEO work and set up Google Tag Manager and LinkedIn Pixel tracking for B2B and B2C lead generation. - Peppernode: built a job platform for Canadian businesses front to back (Next.js, PostgreSQL, Drizzle ORM, Vercel, Stripe), a creator subscription platform with live streaming (React, Vite, LiveKit, Stripe), and a pay-at-table feature for a restaurant chain (Next.js, Stripe terminals). - Solvexus: two data-heavy single-page apps for maritime logistics, where I handle state management and rendering performance on large datasets. - Coderiver: delivered 9 React projects for clients in crypto, fintech and eCommerce. Reusable components cut delivery time on a crypto podcast CMS by 27%. Stack: Frontend: React, Next.js, TypeScript, Vite, Redux, Zustand, React Query, GraphQL, Tailwind CSS, Gatsby Backend: Node.js, Python, Django, Django REST Framework, Celery, pytest, PostgreSQL, Drizzle ORM, Redis Infrastructure: Docker, Vercel, AWS, CI/CD Integrations: Stripe, LiveKit/WebRTC, Google Ad Manager, DV360, Meta and TikTok APIs, Google Tag Manager