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SviatTymonko._

About

Engineer and founder

I'm Sviat, a Tech Lead and technical co-founder based in Warsaw, Poland. I have spent 6+ years in startups and product development as a fullstack engineer: mobile apps, web, desktop and backend. Most of my projects started from an empty repo — I chose the architecture and took them all the way to release on the App Store and Google Play. MVPs are my strongest side.

That is more than 20 products in very different fields: fitness and health, medical documents encrypted on the device, a desktop ground control station for drone operators, social platforms with creators, live video and payouts, education platforms, an HR system, a crypto exchange, e-commerce for a pharmacy chain and AI products.

Building teams, not just code

As a founder, I took on client projects, including from Upwork, put together the team for each one and answered to the client for the result. We delivered an online fitness platform in 8 months with a team of 5, and a farm discovery app in 5 months with a team of 4. That is where I learned to think in products and outcomes, not tasks.

What I work on now

Three client products at once: Mobile Lead on a pharmacy e-commerce app, Senior Fullstack on an AI platform for families, and Senior Mobile at a Ukrainian startup. Alongside them I build my own products, Gymni and Electron Publish Pro. There I own not only the code but the marketing too — positioning, the funnel, content and the first users — so a product does not stall between “built” and “sold”.

How I can help

Build a product from scratch, pull a stuck project back on track, or look at it from the outside — from the technical side and from the side of “why people don't get to the purchase”.

Technologies I have shipped with

Taken from the code of the products I have worked on, grouped by area, with the cases that show them in practice.

Mobile

  • React Native
  • Expo
  • EAS Build
  • Expo Router
  • React Navigation
  • TypeScript
  • Native modules in Kotlin
  • Native modules in Objective-C++
  • Ionic
  • Reanimated
  • Gesture Handler
  • Skia
  • Victory Native
  • Rive
  • Lottie
  • FlashList
  • NativeWind
  • React Native Paper
  • VisionCamera
  • react-native-maps
  • Google Places
  • Bottom Sheet
  • i18next

In practice: Medical documents with on-device encryption · Video calls built from scratch for a fitness platform · An MVP in one month that won the next contract · Gymni: an app and platform for personal trainers · Live sports debates app with real-time audio and video

State, data and forms

  • Redux Toolkit
  • redux-persist
  • TanStack Query
  • Offline query persistence
  • Zustand
  • MobX
  • RTK Query
  • Realm
  • MMKV
  • Immer
  • Apollo Client
  • GraphQL
  • GraphQL Codegen
  • OpenAPI codegen
  • Axios
  • react-hook-form
  • Formik
  • zod
  • Yup

In practice: No-code app builder ready for Web Summit

Desktop

  • Electron
  • electron-builder
  • electron-updater
  • electron-store
  • @electron/notarize
  • @electron/osx-sign
  • macOS hardened runtime
  • Windows and Microsoft Store builds
  • serialport
  • MAVLink
  • Leaflet maps
  • ffmpeg
  • HLS / DASH / RTSP video
  • IndexedDB offline storage
  • pdf.js

In practice: Hiring time cut by 40%

Web

  • React
  • Next.js
  • Vite
  • Webpack
  • Rollup
  • Tailwind CSS
  • shadcn/ui
  • Radix UI
  • MUI
  • Mantine
  • Sass
  • BEM
  • Bootstrap
  • Materialize
  • Moon Design System
  • Vue 3
  • Gulp
  • Storybook
  • Recharts
  • CKEditor 5
  • Three.js
  • Framer Motion

In practice: No-code app builder ready for Web Summit

Backend

  • Supabase Postgres
  • Supabase Edge Functions
  • Supabase Realtime
  • Supabase Auth
  • Firebase Cloud Functions
  • Firestore
  • Firebase Auth
  • NestJS
  • NestJS microservices
  • Express
  • Fastify
  • Ruby on Rails
  • Sidekiq
  • Strapi
  • PostgreSQL
  • MongoDB
  • Firebase Realtime Database
  • Prisma
  • Sequelize
  • Drizzle ORM
  • Redis
  • Swagger / OpenAPI
  • Docker

In practice: Gymni: an app and platform for personal trainers · Live sports debates app with real-time audio and video

Real-time and media

  • mediasoup
  • WebRTC
  • protoo
  • Agora
  • Agora cloud recording
  • LiveKit
  • Stream Chat
  • Pusher
  • Socket.IO
  • WebSocket
  • hls.js
  • ffmpeg
  • react-native-video

In practice: Video calls built from scratch for a fitness platform · Live sports debates app with real-time audio and video

AI

  • OpenAI / ChatGPT
  • Anthropic Claude
  • Perplexity API
  • Vercel AI SDK
  • LangChain
  • AI document parsing

In practice: An MVP in one month that won the next contract

Payments, identity and security

  • Stripe
  • RevenueCat
  • Adapty
  • Fondy
  • TrueLayer open banking
  • Mamopay
  • Paddle
  • Onfido KYC
  • Privy wallet
  • Passkeys
  • AWS Cognito
  • Google and Apple sign-in
  • Auth.js
  • Firebase Authentication
  • Microsoft Graph / MSAL
  • AES-256 and RSA
  • crypto-js
  • SSL pinning
  • Encrypted storage

In practice: Medical documents with on-device encryption · Video calls built from scratch for a fitness platform · Gymni: an app and platform for personal trainers

Growth and observability

  • Firebase Analytics
  • Crashlytics
  • Remote Config
  • Sentry
  • AppsFlyer
  • OneSignal
  • Notifee
  • Firebase Cloud Messaging
  • GA4

In practice: Gymni: an app and platform for personal trainers

Quality and releases

  • Fastlane
  • GitHub Actions
  • GitLab CI
  • CircleCI
  • Over-the-air updates
  • Jest
  • Testing Library
  • Cypress
  • Playwright
  • Vitest
  • React Testing Library
  • SonarQube
  • Docker
  • Husky + commitlint
  • App Store
  • Google Play
  • Vercel

In practice: An MVP in one month that won the next contract

Experience

  1. Now

    Mobile Lead

    Pharmacy e-commerce chain

    Lead the iOS and Android apps on top of Magento and GraphQL: checkout, pharmacy map, loyalty cards, releases to both stores.

  2. Now

    Senior Fullstack

    AI platform for families

  3. Now

    Senior Mobile

    Ukrainian consumer app startup

  4. Now

    Founder

    Gymni · Electron Publish Pro

    Build my own products end to end, from the code to positioning, the funnel and the first users.

  5. Founder

    Product team for client projects

    Took on client projects, including from Upwork, put together the team for each one and answered to the client for the result. Delivered an online fitness platform in 8 months with a team of 5, and a farm discovery app in 5 months with a team of 4.

  6. Jun 2025 –

    React Native Developer

    HealthTech company

    Built a medical documents app from scratch with on-device PDF encryption in native modules; published on the App Store and Google Play.

  7. Jul 2022 – Jun 2025

    React / React Native Developer

    Product company

    Fitness app with in-house video calls (MVP in 2 months, won a new project), a ChatGPT education app (MVP in 1 month, deploy time −50%), and a no-code app builder (alpha for Web Summit in 2 months, 500 active users).

  8. 2022

    Electron Developer

    HR system

    Desktop HR system with a Trello-style hiring board; time-to-hire −40%; signed macOS release.

  9. Mar 2021 – Jul 2022

    React Developer

    Crypto exchange

    Frontend architecture and UI kit; MVP shown to the client in 2 months, securing a new project.

Education
Bachelor in Computer Engineering, King Danylo University (2022–2025)
Languages
Ukrainian (native), English (upper-intermediate)

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