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I’m Andriy Kotko, a senior frontend engineer with 6+ years of experience building production web applications with React, TypeScript, and Next.js. I especially enjoy turning technically complex AI-driven systems—like streaming chat experiences, voice interfaces, RAG knowledge workflows, and real-time GraphQL integrations—into fast, reliable, user-friendly products. Over the years, I’ve owned frontend architecture end-to-end, partnering closely with product and backend teams to take features from early concepts to production. I’ve shipped real-time PWA experiences with push notifications, built typed GraphQL data layers and real-time subscriptions, and improved performance and quality with testing and CI/CD. I’m also comfortable working with distributed teams across the US, UK, Europe, and Asia, and I care deeply about maintainable code and genuinely useful outcomes for users.…I’m Andriy Kotko, a senior frontend engineer with 6+ years of experience building production web applications with React, TypeScript, and Next.js. I especially enjoy turning technically complex AI-driven systems—like streaming chat experiences, voice interfaces, RAG knowledge workflows, and real-time GraphQL integrations—into fast, reliable, user-friendly products. Over the years, I’ve owned frontend architecture end-to-end, partnering closely with product and backend teams to take features from early concepts to production. I’ve shipped real-time PWA experiences with push notifications, built typed GraphQL data layers and real-time subscriptions, and improved performance and quality with testing and CI/CD. I’m also comfortable working with distributed teams across the US, UK, Europe, and Asia, and I care deeply about maintainable code and genuinely useful outcomes for users.

Andrey Kotko

Front-End Developer, Web Developer, Software Engineer, +2

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I’m Andriy Kotko, a senior frontend engineer with 6+ years of experience building production web applications with React, TypeScript, and Next.js. I especially enjoy turning technically complex AI-driven systems—like streaming chat experiences, voice interfaces, RAG knowledge workflows, and real-time GraphQL integrations—into fast, reliable, user-friendly products. Over the years, I’ve owned frontend architecture end-to-end, partnering closely with product and backend teams to take features from early concepts to production. I’ve shipped real-time PWA experiences with push notifications, built typed GraphQL data layers and real-time subscriptions, and improved performance and quality with testing and CI/CD. I’m also comfortable working with distributed teams across the US, UK, Europe, and Asia, and I care deeply about maintainable code and genuinely useful outcomes for users.…I’m Andriy Kotko, a senior frontend engineer with 6+ years of experience building production web applications with React, TypeScript, and Next.js. I especially enjoy turning technically complex AI-driven systems—like streaming chat experiences, voice interfaces, RAG knowledge workflows, and real-time GraphQL integrations—into fast, reliable, user-friendly products. Over the years, I’ve owned frontend architecture end-to-end, partnering closely with product and backend teams to take features from early concepts to production. I’ve shipped real-time PWA experiences with push notifications, built typed GraphQL data layers and real-time subscriptions, and improved performance and quality with testing and CI/CD. I’m also comfortable working with distributed teams across the US, UK, Europe, and Asia, and I care deeply about maintainable code and genuinely useful outcomes for users.

Available to hire

I’m Andriy Kotko, a senior frontend engineer with 6+ years of experience building production web applications with React, TypeScript, and Next.js. I especially enjoy turning technically complex AI-driven systems—like streaming chat experiences, voice interfaces, RAG knowledge workflows, and real-time GraphQL integrations—into fast, reliable, user-friendly products.

Over the years, I’ve owned frontend architecture end-to-end, partnering closely with product and backend teams to take features from early concepts to production. I’ve shipped real-time PWA experiences with push notifications, built typed GraphQL data layers and real-time subscriptions, and improved performance and quality with testing and CI/CD. I’m also comfortable working with distributed teams across the US, UK, Europe, and Asia, and I care deeply about maintainable code and genuinely useful outcomes for users.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Language

English

Fluent

Ukrainian

Fluent

Russian

Fluent

Spanish; Castilian

Intermediate

Work Experience

Senior Frontend Engineer at evLibre (evlibre.cc)

October 1, 2025 - Present

Built a real-time PWA to track EV charge-point availability across Iberdrola’s Spain network, including web push notifications when a port becomes available. Worked solo and shipped to production using React 19 + TypeScript + MUI (Vite), Supabase (Postgres, Edge Functions, Realtime), and a service worker with VAPID for push delivery. Implemented golden-fixture regression testing and an AI-assisted hypothesis-first workflow to support iteration and quality.

Senior Frontend Engineer (Contract) at CloneForce

November 1, 2024 - March 1, 2026

Owned frontend development for an AI digital-clone platform. Built a typed GraphQL data layer (100+ operations) with GraphQL Codegen and integrated Apollo Client into Next.js App Router in an RSC-aware way, including custom cache policies, Auth0 auth bridging, and multi-tenant organization switching. Led an Apollo Client 3→4 migration across the codebase and shipped dual-transport real-time streaming interactions (graphql-ws over WebSockets + SSE) for live clone/meeting events and streaming AI responses. Also contributed to RAG knowledge-base upload UI for large document lists, upgraded voice UX using a custom ElevenLabs React SDK flow plus waveform playback (wavesurfer.js), and implemented OAuth flows (Microsoft, Google, HubSpot) with Auth gating and LaunchDarkly feature flags. Improved performance (reduced load time by ~1.2s) and quality with code-splitting/lazy-loading and substantial Cypress E2E coverage.

Frontend Engineer (Contract) at Human Capital Exchange (HCX)

September 1, 2022 - November 1, 2024

Worked with the founding team on an equity-based asset trading platform. Set up frontend CI/CD with Jest unit tests and Cypress E2E to automate user-flow validation and reduce manual QA. Streamlined multi-role onboarding using JSON Forms and Yup validation with Apollo GraphQL, improving form completion. Simplified payment architecture by removing blockchain libraries and migrating to bank/card transactions to cut operational costs, and integrated DocuSign for in-app KYC/compliance signing. Consolidated MUI theming into shared styles and reusable patterns and authored onboarding documentation to shorten developer ramp-up time.

Frontend Developer at Root Name System (RNS)

November 1, 2020 - June 1, 2022

Built web experiences for a digital-identity platform (rns.id) supporting digital residency. Shipped landing pages, multiple web apps, and a set of HTML email templates. Led TypeScript migration and increased Jest test coverage. Managed complex state with Redux/Redux Toolkit and later migrated to MobX. Integrated i18n localization for 12 languages and supported SSR for improved performance and SEO.

UI Engineer (Contract via Bridge The Gap) at Design-system team (global enterprise)

August 1, 2019 - January 1, 2020

Worked on a design-system team for an enterprise across web and React Native in an Nx monorepo. Added 10+ components and refactored existing components to meet WCAG standards, including running an accessibility audit. Built a design-token structure to streamline design-to-code workflows and migrated documentation to Storybook to improve developer usability and consistency.