Andrii Maksymov

Andrii Maksymov, Senior Frontend Engineer

React, TypeScript, Next.js

I build frontends for data-heavy B2B SaaS. On several products I've been the founding, sole or lead frontend engineer, owning the architecture, the typing and the tests.

Selected work

Client work is text only. Personal projects have screenshots and live links.

aivo Revisions AGSenior Frontend EngineerJun 2024 – Present

Modernizing a live audit platform without a feature freeze

Text only: the product holds clients' financial ledgers, so there are no screenshots here.

Context

aivo is a Swiss audit SaaS based in Zurich. When I joined in June 2024, its frontend was a four-year-old React 17 app, mostly JavaScript, with three styling stacks, hand-rolled data fetching and no test suite.

It works with real client ledgers, and feature work couldn't pause while the foundations changed. So none of what follows happened in a rewrite branch. It went in module by module on the live app.

What I did

  • Data-analysis workspace. I led the frontend of the product's new module for audit data work outside Excel: ledger import, validation, account mapping, pivot tables and saved views. Its structure is now the template for new features.
  • Strict TypeScript, no freeze. Took the 1,500-file app from 11% to 99% strict TypeScript in six milestones while features kept shipping, and ran the React 17 to 18 upgrade.
  • Tests that check the figures. Wrote about 520 of the 620 test files and most of the Playwright end-to-end suite. The import spec had 170 assertions, and not one of them checked a figure. I added a test that compares every imported account total against an independent calculation.
  • Server state and design system. Moved all server state to TanStack Query, with query-key factories and inline keys banned by lint. Replaced Redux with Zustand and URL state, and merged three styling stacks into one MUI design system of about 50 components.
  • API contracts. Added Zod validation on API responses and a contract test registry checked against the OpenAPI spec. It caught three places where the client had silently drifted from the API.
  • Performance and accessibility. Fixed an editor render loop that hit about 400 re-renders per second, and virtualized the ledger table. In CI, axe runs on every Storybook story; the known-failure list went from 513 to 489.

MovadexSenior Frontend Engineer

Founding frontend engineer on a multi-tenant SaaS

Text only: a Movadex client's product, so it stays unnamed and there are no screenshots.

Context

A peer-forum SaaS for business executives, built at Movadex for a client. I wrote the first commit and took it to production.

What I did

  • Ownership. Wrote over 90% of the 52k-line codebase: 733 commits and 185 of its 196 PRs, in React 19, strict TypeScript, Vite, Tailwind and TanStack Query.
  • Product scope. 13 product domains and 46 routes, including the super-admin panel, meeting-cycle forms, engagement analytics, a rich-text community feed and data import with row-level validation.
  • Multi-tenancy. One deployment serves every tenant. I designed it with runtime tenant theming and per-tenant privacy rules.
  • API layer. A typed TanStack Query layer over 200+ endpoints, and the HTTP client under it: silent JWT refresh with request replay, retries with backoff, and normalized typed errors.
  • AI features. Meeting analysis, action-item extraction and reminder drafts on OpenAI, Gemini and Groq, behind one provider interface with ordered fallback and per-attempt timeouts.

Personal projects

Built and run on my own, outside client work.

Experience

2017 to now · fully remote since 2022

  1. Jun 2024 – Present
    Remote

    Senior Frontend Engineer, aivo Revisions AG (Swiss audit SaaS, Zurich)

    Part-time contract alongside my full-time Movadex role Jun 2024 – May 2026; main engagement since Jun 2026.

    Stack: React 18, TypeScript, TanStack Query, Zustand, MUI, Storybook, Jest, Playwright, AWS Amplify

    • Led the frontend of the data-analysis workspace, took the app from 11% to 99% strict TypeScript, and wrote ~520 of its 620 test files.
    • 500+ merged PRs since June 2024, about half the repo's total. I own the frontend CI/CD (GitHub Actions, AWS Amplify) and wrote the testing and architecture docs plus three decision records (ADRs).
    Read the case study for aivo Revisions AG

  2. May 2022 – Jun 2026
    Remote

    Senior Frontend Engineer, Movadex (product agency)

    Full-time.

    Stack across projects: React 19, TypeScript, Next.js, Vite, Tailwind, MUI, TanStack Query, Zustand

    • Founding frontend engineer on a multi-tenant peer-forum SaaS for business executives, from first commit to production.
    • Sole frontend engineer on a humanitarian aid-logistics platform delivered in six months: role-based workflows, inventory, legal documents, maps and EN/UK localization.
    • Also a customer-facing analytics platform, a German-market Next.js SSR/SSG search site (Lighthouse 90+, LCP under 1 s) and an e-commerce site on the Next.js App Router with Payload CMS and Stripe.
    • Supported junior developers for a short period, sharing practices and helping them through their tasks.
    Read the case study for Movadex

  3. Oct 2021 – Apr 2022

    Frontend Engineer, Rivo Agency

    • Refactored a Next.js beauty-services platform and built landing pages that scored Lighthouse 92+ with green Core Web Vitals. Also built CRM features and took part in technical planning.

  4. Jul 2017 – Sep 2021
    Rivne, Ukraine

    Frontend Developer, PRO-IT

    React Developer Nov 2020 – Sep 2021; HTML/CSS Developer Jul 2017 – Oct 2020.

    • Moved from HTML/CSS into React and Next.js. Built a B2B video-player product site and an embed-script generator, and wrote responsive markup and shared CSS for a large B2C video-hosting product.

How I work

Skills

Frontend
TypeScript (strict), JavaScript, React, Next.js (App Router, React Server Components, SSR), HTML, CSS
State management and data
TanStack Query, Zustand, Redux Toolkit, React Hook Form, Zod, REST, WebSockets
Testing
Jest, Vitest, React Testing Library, Playwright, Mock Service Worker (MSW), axe
Quality
accessibility (WCAG 2.1 AA), performance (Core Web Vitals, virtualization), i18n, Feature-Sliced Design
UI and design systems
MUI (Material UI), Tailwind CSS, shadcn/ui, Storybook, Figma tokens, TanStack Table
AI-assisted development
Claude Code and OpenAI Codex (daily), Cursor, GitHub Copilot
Build and delivery
Vite, Webpack, monorepos, CI/CD (GitHub Actions), AWS Amplify, Vercel
Backend (working knowledge)
Node.js, NestJS, Express, PostgreSQL, Prisma, Supabase, LLM APIs

About

I started in web in 2017, writing HTML and CSS at PRO-IT in Rivne, and moved to React and Next.js in 2020. Before that I studied hydropower engineering.

The part of frontend I enjoy most is the unglamorous half: type migrations, test suites, design systems and the API layer everything else depends on.

Based in
Ukraine (UTC+2/+3)
Education
M.Sc., Hydropower EngineeringNational University of Water Management and Natural Resources, 2011 – 2017
Languages
English: B2 (upper-intermediate), used daily at work
Ukrainian: native

Contact

If you have a frontend that has grown faster than its architecture, or a product where the UI is the hard part, I'd like to talk.

[email protected]

Remote, open to roles worldwide · B2B contractor or employer of record (EOR)