Built a spaced-repetition learning platform from scratch -- API, database, authentication and client -- with a rich-text card editor, an analytics dashboard and full English/Ukrainian localization.Architected the client on Feature-Sliced Design (features, entities, widgets), keeping product logic separated from UI as the application grew.Made the stack type-safe end to end: Zod schemas generated from the Prisma model reach the client through tRPC, so a data-model change surfaces as a compile-time error instead of a runtime bug.Built the scheduling layer around the FSRS interval-repetition algorithm (ts-fsrs): card state and review history, batch review of a card set in a single transaction, and timezone-correct review dates through Temporal.Migrated authentication from NextAuth to Better Auth with Google and Discord OAuth, and built the card editor on Lexical (tables, code blocks, hashtags, mentions, Markdown import/export).Modernized the toolchain: ESLint/Prettier to Biome/OXC, migration to Bun, and Docker deployment.Set up the monorepo with turborepo and pnpm workspaces (scaffolded with create-better-t-stack), sharing types and configs across web/packages.

Technologies: Next.js 16, TypeScript, React 19, tRPC, Prisma, PostgreSQL, Better Auth, ts-fsrs, Temporal, Lexical, Zustand, TanStack Query, Zod, Tailwind CSS, shadcn UI, next-intl, Recharts, Biome, OXC, Bun, Docker, Netlify

Developed the core platform architecture of a white-label community platform for medical professionals and healthcare organizations, and its further adaptation for various medical associations.Implemented domain-specific functionality: medical documentation management, hospital-based user roles, and automated email digest systems.The platform serves as a foundation for deploying branded expert networks: discussion feeds, clinical protocol management, and role-based access control tailored for hospitals and clinics.

Technologies: React, TypeScript, Vite, MobX, Ant Design, Styled Components, Lexical, Axios

Created the project from scratch and maintained it further: a network of advisors and financial service providers assisting with mortgage repayment and tax reduction.

Technologies: Next.js, TypeScript, React Query, Ant Design, Recharts, Styled Components, Framer Motion

Created an SEO-friendly job search application using hybrid static and server rendering.Wrote unit and integration tests.

Technologies: TypeScript, React, Redux, Redux-Saga, Redux Toolkit, Jest, React Testing Library, Cypress, React Hooks, i18next, Styled Components, TSDoc, Webpack, Reselect, Chakra UI, Ant Design, Ramda

Placed by a staffing agency as a contract frontend developer at three end clients in travel, affiliate marketing and information security; owned the client-side work on each product, worked on several of them in parallel as the sole frontend developer, and did bugfixing and refactoring of legacy code throughout, including React Native (mobile) work.

Gazinformservice -- network and security monitoring tools (Dec 2020 - May 2021): built web versions of programs for monitoring the configurations and states of network equipment, information security tools, virtualization platforms and operating systems; beyond writing functionality, a large share of the work was bugfixing and optimizing application performance.

Clicklead -- affiliate/CPA platform (Apr 2020 - Dec 2020): developed the affiliate dashboard -- statistics by offer, GEO and period with grouping and filters -- and owned the payouts scenario: wallet selection, request creation, status tracking, and operation history with filters by amount, currency and date.

Onlinetours -- travel aggregator (Jan 2019 - Apr 2020): built a travel aggregator for finding and booking trips -- a catalog covering many destinations, hotels and tour packages, with search and filtering by dates, number of guests and price, plus a multi-step booking form; developed the search, filtering and offer-list interface in React with TypeScript (Redux, Redux-Saga), built booking forms with validation and server-error handling, and maintained a component library in Storybook with unified styles in CSS Modules; refactored legacy code and optimized catalog page performance.

Technologies: React, React Native, React Hooks, TypeScript, Redux, Redux-Saga, MobX, Redux Actions, Reselect, Formik, Ant Design, Material UI, SCSS Modules, CSS Modules, Storybook, Webpack, Gulp, Jest, React Testing Library, i18next, TSDoc