Frontend engineer obsessed with performance, design systems, and turning complex ideas into smooth, elegant interfaces. I love building things that scale and feel great to use.

Serhii Rivniy

Frontend engineer obsessed with performance, design systems, and turning complex ideas into smooth, elegant interfaces. I love building things that scale and feel great to use.

Available to hire

Frontend engineer obsessed with performance, design systems, and turning complex ideas into smooth, elegant interfaces. I love building things that scale and feel great to use.

Experience Level

Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
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Language

English
Advanced
Russian
Fluent

Work Experience

Senior Front End Software Engineer at Charity Inc (Stratly SaaS CRM)
September 1, 2025 - October 2, 2025
Led the frontend of a white-labeled SaaS CRM + donation/membership platform (Stratly) used by charities. Delivered internal CRM modules and customizable donor forms, architected and maintained React/Next.js (BFF) apps in a monorepo, and implemented visual workflow automation using React Flow. Built a form builder with conditional logic, validation rules, and a delivery queue for form configurations. Implemented a micro-frontend setup with per-route/role loading and shared libraries (RBAC, UI kit) for easier brand customization and safer releases. Managed real-time channels via WebSocket/SignalR, added an ID-based message queue with delivery guarantees, and supported offline/online reconnection and mobile UX. Optimized complex chart Rendering (Visx) with memoization, virtualization, off-screen canvases, throttling/debouncing and lazy loading. Integrated Material UI + Storybook-driven components, theming aligned to Figma specs, and established unit/integration tests (Jest, Testing Librar
Senior Front End Software Engineer at Global Teams, FinTech
November 1, 2023 - October 2, 2025
Built and evolved a white-label B2B fintech platform (multi-brand trading terminal, admin dashboard, UI Builder, real-time trader/lead management). Designed client/admin architecture and rewrote legacy admin from PHP to React (TypeScript), modularizing features and enabling faster brand customization and safer releases. Implemented a micro-frontend setup with per-route/role loading and shared libraries (e.g., check access, UI kit), feature flags, data versioning, and migration utilities for backward compatibility. Managed parallel WebSocket/SignalR channels (charts, balances, notifications) and added an ID-based message queue with delivery guarantees and auto-reconnect. Migrated complex chart rendering to a high-performance canvas (Visx) with memoization, virtualization, off-screen canvas, throttling/debouncing and lazy loading. Combined Material UI with a Storybook-driven component library. Introduced JSON theming (colors, typography) and aligned with Figma specs. Established unit/int
Senior Front End Software Engineer at Life Line Labs
March 1, 2020 - October 2, 2025
Built a PWA health care platform (EMR, scheduling, lab results) for patients and doctors. Implemented offline-first flows with service workers (offline caching, session-scoped caching, conflict resolution). Ensured security/compliance aligned with Malaysia’s PDPA: JWT auth with refresh, centralized RBAC, restricted caching, HTTPS/CORS hardening. Integrated patient history, lab results, and bookings, authored API docs, and onboarded internal notes. Delivered reusable UI with automatic design tokens aligned to Sketch handoffs. Wrote unit tests and end-to-end tests; collaborated with PMs, designers, and QA to maintain coding standards and consistent UI quality.
Senior Frontend Software Engineer at Micharity Inc
September 1, 2025 - October 2, 2025
Built and evolved a SaaS CRM + donation/membership platform (Stratly) used by charities and non-profits. Led the architecture of React/Next.js (BFF) monorepo apps, implementing a visual workflow automation editor with React Flow (draggable, nestable conditions, triggers, activity nodes) and a JSON-driven form builder with conditional logic and validation. Designed and integrated public-facing forms with responsive Material UI-based UI, theming tokens aligned to Figma specs, and a reusable UI system. Delivered unit and integration tests (Jest, Testing Library) and end-to-end tests (Cypress). Set up GitHub Actions pipelines and maintained dev/QA/workflow standards. Drove performance optimization, server- and client-side rendering improvements, and a scalable release process.
Senior Frontend Software Engineer at Confidential FinTech
November 1, 2023 - October 2, 2025
Built and evolved a white-label B2B fintech platform (multi-brand trading terminal, admin dashboard, UI Builder, real-time dashboards). Rewrote legacy PHP admin to React (TypeScript) with modular design, enabling faster brand customizations and safer releases. Implemented a micro-frontend setup with per-route modules and shared libraries (UI kit, RBAC concepts, feature flags) and data versioning/migration utilities for backward compatibility. Managed parallel WebSocket/SignalR channels (charts, balances, notifications) and added an ID-based message queue with delivery guarantees, auto-resend on reconnect, offline/back-pressure handling, and mobile browser compatibility. Migrated charts to a high-performance canvas pipeline with memoization and virtualization; introduced design tokens and a Material UI + Storybook-driven component library. Added unit tests (Jest) and end-to-end tests (Cypress) for spins and edge cases; integrated GitHub Actions CI and Vercel deploys with robust QA gates
Senior Frontend Software Engineer at Life Line Labs
March 1, 2020 - October 2, 2025
Built a Progressive Web App healthcare platform (EMR, scheduling, lab results, video consults) for patients and doctors. Implemented offline-first flows with Service Workers: session-scoped caching, offline results/history, auto-sync on reconnection, and conflict resolution (doctor-first). Ensured security/compliance per PDPA: JWT auth with refresh, centralized error handling, RBAC, restricted caching, HTTPS/CORS hardening. Integrated patient history, lab results, docs, and bookings; authored API docs, onboarding guides, and internal notes. Delivered reusable UI via atomic design, and completed tests (Jest, Mocha, Chai) plus end-to-end tests (Cypress). Collaborated with PMs/designers/QA to maintain consistency and accelerate delivery.
Senior Frontend Software Engineer at Azart.world
January 1, 2022 - October 2, 2025
Built and shipped HTML5 real-money games and tooling: 3- and 5-reel slots with free-spins/double-win features, and an admin suite to configure, brand, and version games for desktop and mobile browsers. Designed a reusable slot engine with clean separation of math/logic, animation, and rendering layers. Game behavior (reels, paylines, bets, RTP, volatility, bonuses) was JSON-driven, enabling rapid skinning and new title creation with minimal core changes. Implemented a high-performance canvas pipeline using PixiJS, Spine, and GSAP timelines, optimized texture atlases via TexturePacker, and implemented adaptive frame-rate mode for low-end devices while preserving smoothness. Connected user wallets and stake/logic via REST/WebSocket APIs; added multilingual and multi-currency UI with locale-aware formatting. Wrote unit tests (Jest) and end-to-end tests (Cypress) for spins and edge cases.

Education

Master of Information Technology at Donbass Mechanical Engineering Academy, Ukraine
January 11, 2030 - October 2, 2025
Master of Information Technology at Donbass Mechanical Engineering Academy, Ukraine
January 11, 2030 - October 2, 2025

Qualifications

Add your qualifications or awards here.

Industry Experience

Software & Internet, Financial Services, Healthcare, Gaming, Non-Profit Organization

Experience Level

Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
See more

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