Senior Front-End Engineer

Kostiantyn
Keilin

15+ years building enterprise-grade interfaces. Specialising in React, TypeScript, micro-frontends, and config-driven architecture.

Get in touchGitHub ↗
15+
Years of experience
9+
Years in React/TS
01 — About

Who I am

I'm a Senior Front-End Engineer with over 15 years of experience, based in Toronto, Ontario, Canada. My focus is on building scalable, maintainable enterprise UIs — the kind that stay coherent as codebases grow.

I gravitate toward config-driven architecture, Feature-Sliced Design, and micro-frontend patterns. Most recently I worked on a fintech platform at RBC Capital Markets via EPAM, where I brought a critical dashboard from ~2 seconds load time down to 32ms through prioritised data fetching.

I write about engineering trade-offs on Medium and LinkedIn — mostly about the stuff that doesn't fit in tutorials.

Open to new opportunities
Kostiantyn Keilin
LocationToronto, Ontario · Canada
FocusSenior FE / Senior Software Engineer
Core stackReact · TypeScript · Next.js · Redux
Phone+1 905 962 1211
02 — Projects

What I've built

// config-driven-testimonials
A React component library for rendering testimonial blocks from a config. Published on NPM. Fully typed Zod schema for runtime validation — the config drives everything, components know nothing about the source. Built in a Turborepo monorepo with a live Next.js demo and settings generator.
ReactTypeScriptZodTurborepoNext.jsNPM
// slotpaste
A personal clipboard for form-filling. Store reusable snippets — names, addresses, boilerplate — and paste them into forms without dragging styles along. The canvas view lets you group snippets spatially, which turned out more useful than a flat list. Started as an Electron app, moved to PWA after hitting performance issues. Includes a private mode with encryption.
ReactTypeScriptTailwindPWA
// playshelf
A test-task project that became an interesting architecture experiment. Real-time sync across browser tabs, no backend — everything runs in localStorage with 300ms simulated latency. Built with Next.js and Radix UI as required by spec.
Next.jsTypeScriptRadix UIlocalStorage
03 — Experience

Companies I've worked with

2022 – 2026
EPAM Systemsvia First Derivatives · Client: RBC Capital Markets
Senior FE Engineer
2020 – 2022
VarteqEnterprise product development
Senior FE Engineer
Mar–Sep 2020
TrinetixClient: Deloitte
FE Engineer
2018 – 2020
LitslinkSoftware development studio
FE Engineer
2017 – 2018
Arnit
FE Engineer
2011 – 2017
Earlier experienceVarious agencies and freelance
Web Developer
04 — Skills

What I work with

Core
ReactTypeScriptNext.jsReduxJavaScript
UI & styling
MUITailwindRadix UIAG-GridStyled ComponentsCSS Modules
Architecture
Micro-frontendsModule FederationFSDConfig-drivenTurborepo
Testing & quality
JestReact Testing LibraryPlaywrightaxe-coreWCAG 2.1 / AODA
Tooling & infra
ViteWebpackBabelGitHub ActionsVercelAWS (S3, Lambda)SupabaseZod
Other
AngularNode.jsGitRESTGraphQL
Soft
Technical writingCode reviewMentoringEnglish (C1)
05 — Testimonials

What people say

// config-driven-testimonials — live integration

The testimonials above are rendered directly from my open-source npm package. A single JSON config drives everything — layout, content, avatars. No backend, no CMS. Drop it into any React app and it just works.

npm install config-driven-testimonials
07 — Contact

Let's talk

I'm actively looking for my next role in fintech or enterprise front-end. If you're building something interesting and need someone who thinks about architecture as hard as they think about code — reach out.

keilinkostiantyn@gmail.com
Toronto, Ontario · Canada
+1 905 962 1211
koskei.com