AndriiButenko

IT outsourcing company — client project: multi-brand consumer web platform, 30+ locales (under NDA).

Team: 7 engineers (frontend and backend), designers, product owners

• Shipped features and fixes across an Astro/TypeScript monorepo and its Spring Boot backend, e.g. fixed framed QR codes that rendered broken in Safari and in PNG/JPEG exports by embedding the code as a nested SVG instead of a foreignObject; also fixed a production error found through Sentry, where quotes in translations broke Alpine.js expressions.
• Built custom highlight colors for CMS-edited rich text end to end: Spring Boot validation, server-side rendering that allows only strict hex values into inline styles, and rules for the LLM translator.
• Moved the shared client JavaScript (15 modules, ~4.6k lines) out of the Spring Boot app into a frontend package, then deleted the backend copy after checking CDN analytics.
• Launched 8 A/B and painted-door tests on landing pages, funnels and paywalls with the in-house experiment framework, keeping the control arm byte-identical, and cleaned up 9 finished experiments by removing the losing variant and its wiring.
• Redesigned the flagship site's footer with a language picker for its 32 locales (reused in the shared footer of four other brand sites) and added a build-time check that fails when a site's locales, translation bundles and language names disagree.

Websites built to order: VM Design (interior architecture studio) and Grosters

vmdesignproject.com • grosters.com

• VM Design: built a multilingual (EN/FR/IT/RU/UK) Astro site with Zod-typed Markdown collections: 22 projects, 216 static pages (165 indexable) and an astro:assets / sharp image pipeline producing 4,500+ AVIF/WebP variants; Lighthouse 100 in all four categories on desktop, 96+ Performance and 100 in the rest on mobile, CLS 0.
• VM Design: wrote interactive components in vanilla TypeScript (before/after slider, carousel, native-dialog lightbox, WebGL gallery on OGL); replacing a React island cut gallery JS from ~290 KB to 65 KB (−77%).
• VM Design: implemented technical SEO across five locales: localized meta, canonical + hreflang, i18n sitemap, JSON-LD (ProfessionalService, BreadcrumbList, CreativeWork) and 1,384 translated image alt texts.
• VM Design: set up CI/CD from GitHub Actions to Cloudflare Workers with a custom domain, DNS and long-term asset caching; generated SVG region maps from GeoJSON (no map library) and a Python pipeline that redacts client data from 199 PDF drawing sheets.
• Grosters (grosters.com): shipped a 4-page mobile-first commercial site solo, from requirements to production; optimized images and loading — Lighthouse 99 Performance / 100 Best Practices / 91 Accessibility (LCP 0.8 s, CLS 0).

Regulated online casino: 3 brands in one monorepo; licences UKGC, DGOJ (Spain), Sweden, MGA.

Team: 1–2 developers, QA, PM

• Delivered 38 merged PRs in four months (196 files changed): Figma-to-code UI, mobile layouts and QA fixes across the lobby, jackpots, VIP, promotions and game-category pages.
• Prepared the Swedish market launch: market-level feature flags that remove unavailable sections (welcome bonus, live casino) from routes, navigation and sitemap, Swedish currency formatting, and a fix for the platform web components serving English legal documents.
• Fixed an i18next initialization race that left raw translation keys in the navigation on 46 of 50 cold page loads (92%).
• Consolidated typography into one named scale (57 arbitrary font sizes removed), raised mobile touch targets to 44px and fixed an iOS Safari sticky-header flicker.

Multi-module CRM platform for real-estate agencies (pre-release).

Team: developers, QA, designers, product owner

• Cut the main JavaScript chunk by 45% (621 KB to 341 KB gzip) and first-load JS by ~48% by moving 33 pages to React.lazy + Suspense, with a chunk-load error boundary and idle-time prefetching.
• Made react-hooks/exhaustive-deps and rules-of-hooks errors and cleared the ESLint backlog (225 problems to 0) across 92 files; reorganized 53 root-level components into 21 domain-based folders.
• Rebuilt the deal details view from Figma: activities, notes CRUD and linked-property sections with scroll-spy navigation (IntersectionObserver).
• Fixed 15 defects across Deals, Properties, Profile, Contacts and Documents, e.g. timezone-shifted activity times and HEIC / oversized photo uploads (client-side JPEG compression, HTTP 413 handling); moved hard-coded strings to i18next (EN/UK).

Clinical data de-identification platform for healthcare providers (under NDA).

Team: 4 developers

• Built passwordless magic-link authentication end to end: a NestJS auth module (2 REST endpoints, TypeORM migration, single-use 256-bit tokens, JWT issuance, Swagger docs) and the React sign-in / verify flow with react-hook-form + yup.
• Built the UI of a 4-step clinical-data de-identification wizard: custom stepper synced with the sidebar via Redux Toolkit, upload validation (5 MB / 250k characters) with progress feedback and responsive styling.
• Developed the app shell (dashboard layout, collapsible sidebar, top bar, support modal) and dashboard page for desktop and tablet; handled JWT session expiry with a 401 interceptor guard and a Session Expired page.