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I'm Nikita Kolosov
Software Engineer
Portfolio
Check out my featured projects
NK MeetCross-platform meeting app built with React Native, Expo Router, and LiveKit: create or join rooms, shareable room links, recent meetings, and real-time audio/video controls.
Protein WebInteractive drug-discovery game: guide molecules into real cancer-target proteins with live 3D visualization and physics-based binding scoring.
Auth ServiceGo authentication microservice for BLOB: email/password and social sign-in, rotating JWT sessions, account recovery, rate limiting, and hardened HTTP security.
Golang Todo AppREST API backend in Go with PostgreSQL and Docker Compose: a single `make start` spins up the database, applies migrations, and launches the service.
About me
Solving complex tasks in a user-friendly application
×1.4
app performance gain via profiling
87%
Unit + E2E test coverage
×1.37
lower monthly server costs
AA
WCAG 2.1 AA accessibility I build and test to
Web developer with 5+ years of experience in high-load applications and distributed systems.
I take on complex products: performance profiling, architecture, and unit and E2E tests - with attention to detail and accessibility (a11y).
Name
Nikita Kolosov
Email
NKolosov097@gmail.com
Resume
Download CVEducation and practical experience
From a Computer Science degree to production-grade products - I build full-stack applications with React, Next.js and Node.js, from real-time video (WebRTC) to AI agents. Below is a snapshot of my education, work experience and the tools I reach for every day.
My education
| 2023 | Yandex PracticumFrontend Developer | Covered the full frontend cycle: built several SPAs on React, Redux Toolkit and client-side routing - from markup and animations to secure auth, WebSocket and deployment. Configured Webpack builds and linters; every project passed mentor code review. |
| 2021-2022 | HexletJavaScript Developer | Built the JavaScript engineering foundation: OOP and abstraction through data, asynchronous programming, network protocols, TypeScript. Wrote tests and semantic markup, submitting every task through code review. |
| 2020-2024 | University MAISystem analysis | Academic foundation under the applied work: programming in C, C++, Python and JS, databases, information security, artificial intelligence and higher mathematics. Built models on real datasets: regression, classification and clustering. |
Work experience
- 2024present
Proofix · Senior Software Engineer
- Real-time video conferencing platform, owned end-to-end from FE↔BE contract to production observability.
- Cut monthly server costs 27% with a 1 room = 1 server architecture that eliminated idle resource allocation.
- Improved React rendering 1.4× by profiling the component tree and removing unnecessary re-renders.
- Raised test coverage from 0 to 87% with Playwright and React Testing Library on an untested codebase.
- Shipped AI interview agents (voice + text) and a facial-expression-analysis agent end-to-end, plus Document Picture-in-Picture.
- Architected real-time features on WebSocket, WebRTC and LiveKit, with observability via ElasticSearch and DataDog.
- Next.js
- LiveKit
- WebRTC
- Web Workers
- Framer Motion
- Playwright
- React Testing Library
- Redux Toolkit
- i18next
- Node.js
- Redis
- ElasticSearch
- DataDog
- 20222024
Everypixel Workroom · Frontend Engineer
- AI-native creative platform for video and image generation, leading the frontend architecture end-to-end.
- Aggregated 10+ third-party AI models (Kling, Runway, Veo, Wan, Seedance) into a single editing workflow with real-time progress.
- Owned the FE↔BE contract - REST schemas and WebSocket protocols - removing ad-hoc endpoints.
- Built a virtualized media library with @tanstack/react-virtual for thousands of assets without layout thrashing.
- Delivered race-condition-free uploads with react-dropzone and async-mutex and an accessible (WAI-ARIA) design system on Radix UI.
- Integrated Sentry across the React Router 7 app and enforced consistency via an ESLint / Prettier / Stylelint / Husky pipeline.
- React 19
- React Router 7
- Redux Toolkit
- React Hook Form
- Zod
- Radix UI
- Framer Motion
- @tanstack/react-virtual
- react-dropzone
- async-mutex
- Sentry
- TypeScript
- Vite
- SASS
- 20212022
Divergent · Frontend Developer
- Product engineering and outsourcing, delivering 3 internal products from zero to production for hundreds of users.
- Replaced a manual report-creation process with a drag-and-drop document/report constructor built on React DnD.
- Reduced support response times with a real-time chat featuring presence indicators and message history.
- Eliminated runtime validation bugs by enforcing React Hook Form + Zod schemas across all forms.
- Standardized development environments with Docker, removing works-on-my-machine issues across the team.
- React
- React Hook Form
- Zod
- React DnD
- Docker
My favorite tools
React
NextJS
React Hook Form
Zod
RTK Query
Zustand
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Framer Motion
Jest
Cypress
Playwright
NestJS
PostgreSQL
When I'm not writing code…
A fully playable DOOM, compiled straight to WebAssembly - no DOS emulator, just the original 1993 engine running at native speed in your browser.
Writing
Articles, notes and talks
- My blogTwo States Are EnoughA response to Lea Verou's case against tri-state dark mode toggles - and why two states plus a smart localStorage default aren't just simpler UX, they're the version that's actually easier to implement correctly.
- My blogCompiling Isn't Shipping: What AI Boilerplate Still Leaves for Senior EngineersAI closes the distance on typing code. It never closed the distance on owning it - here is what still requires a senior engineer in 2026.