Oleksii

Oleksii Khivrenko
Frontend Engineer · React · TypeScript · Next.js
Warsaw, Poland · Open to Remote, Hybrid & On-site (EU)
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SUMMARY

Frontend engineer with 8+ years of experience, mostly working with React and TypeScript. I enjoy building things from
scratch and figuring out complex business logic on the frontend - over the years I've shipped products across retail supply
chain, construction SaaS, pharma, real estate, fintech trading, and (re)insurance. Comfortable with greenfield work as
well as scaling and modernizing legacy systems. I also care a lot about performance, testing, and clean architecture.

TECHNICAL SKILLS

Languages: TypeScript, JavaScript (ES6+), HTML5, CSS3, SASS
Frameworks & Libraries: React, React Native, Next.js, Redux (Toolkit / Saga / Thunk), Node.js
UI & Data: TanStack React Table, Chart.js, D3, Recharts, MUI, Ant Design
Forms & Validation: React Hook Form, Formik, Yup
Testing: Jest, React Testing Library, Cypress, Enzyme
Architecture: Micro-frontends, NX Monorepo, GraphQL, REST APIs, WebSockets
Code Quality: ESLint, Prettier, SonarQube, Checkmarx
CI/CD & Tooling: GitHub Actions, CircleCI, Argo, Spinnaker, Webpack
Monitoring: Datadog, New Relic, Opsgenie
AI & Productivity: GitHub Copilot, AI-assisted development workflows
Methodologies: Agile (Scrum, Kanban), Code Review, Mentoring

PROFESSIONAL EXPERIENCE

Senior Software Engineer • SoftServe Aug 2021 – Present
Remote
Senior frontend engineer on long-term client projects across retail, construction SaaS, pharma, and real estate. Take part
in architecture decisions, mentor teammates, and handle work from requirements all the way to production.
Supply Chain Planning Platform - Top-5 UK grocery retailer · 1+ year
Stack: React, Next.js, TypeScript, TanStack Table, React Hook Form, Chart.js, Jest, RTL, SonarQube, Checkmarx, GitHub Actions.
▸ Built an enterprise planning platform almost from scratch (greenfield), shaping the core business logic and frontend
architecture with React, Next.js, and TypeScript.
▸ Built 20+ data tables with TanStack React Table on top of a custom config layer (30+ properties) - sorting, pagination,
resizing, complex inline editing.
▸ Made advanced forms with React Hook Form, including custom validation rules and dirty-state handling so users
don't lose unsaved changes.
▸ Worked out the financial year and period-based business logic on the frontend, talking to several backend services.
▸ Made interactive KPI dashboards with charts Chart.js synced to the table data so users can explore numbers live.
▸ Pushed page load to a 90+ Lighthouse score with code-splitting, memoization, fewer re-renders, and cleaning up the
data flow.
▸ Kept unit test coverage above 90% with Jest and React Testing Library.
▸ Kept the code clean for SonarQube and Checkmarx.
▸ Used AI Tools and GitHub Copilot to speed up secure-coding fixes and development process.
▸ Worked with CI/CD pipelines in GitHub Actions and wrote technical docs in Confluence.

Construction Management SaaS Platform - Leading US construction software provider
Stack: React, TypeScript, Ruby on Rails, MFE, Jest, RTL, Okta, Argo, CircleCI, Datadog.
 ▸ Built new features in a Micro-Frontend (MFE) setup that lived alongside a legacy Ruby on Rails app.
▸ Helped move UI components into the new MFE so the team could gradually retire the old code.
▸ Built a new file uploader to help customers migrate to the updated UI.
▸ Fixed security issues and stability problems affecting enterprise customers.
▸ Watched production health with Opsgenie, Datadog, and New Relic, and reacted to incidents across other services.
Pharmacy Management Platform - Leading US specialty pharmacy
Stack: TypeScript, React, Redux Toolkit Query, NX Monorepo, MUI, Auth0, Azure, .NET API, Jest, RTL.
▸ Built a new app from scratch with React, TypeScript, and a .NET backend, inside an NX Monorepo with shared
component libraries.
▸ Made role-based micro-frontends and reused a custom component library across the platform.
▸ Added multi-theme support with MUI and i18n for a multi-country rollout.
▸ Hooked up Okta / Auth0 for authentication.
▸ Built a CSV uploader and a custom DataTable with static columns, reordering, and sorting.
▸ Got to around 80% test coverage and wrote technical docs for the team.
Real Estate Platform - Major US/EU real estate franchise · ~2.5 years
Stack: React, TypeScript, Redux (Thunk/Toolkit), Next.js, GraphQL, Google Maps API, Webpack, Datadog, Spinnaker, CircleCI.
▸ Worked across 5+ apps in a micro-frontend setup, building features for listing display, editing, and creation.
▸ Built map-based features with the Google Maps API - drawing boundaries, plotting listings and neighborhoods, popup
details.
▸ Made client-side and server-side filtering and sorting used across multiple apps.
▸ Built shared components (data tables, notifications, error handling) reused across the product suite.
▸ Used GraphQL with useQuery for data fetching, and added user role management.
▸ Added multi-language support and contributed JSDoc comments across the codebase.
▸ Took part in code reviews, sprint demos, risk assessments, and other Agile rituals.

Frontend Software Engineer • Codeit LLC Jun 2018 – Aug 2021
On-Site
Long-term product work in fintech trading and (re)insurance - mostly real-time data UIs, complex visualizations, and
shared frontend systems.
Exposure Management Platform for (Re)Insurers - French (re)insurance analytics company · 1 year
Stack: React, JavaScript, SCSS, Ant Design, Ant Design Charts, Recharts, Google Maps API.
▸ Built UIs for an exposure management platform used by specialty (re)insurers to analyze, manage, and price risks
across energy, property, and political violence lines.
▸ Built sortable and filterable data tables for risk submission and exposure analysis, working with large datasets and
complex financial criteria.
▸ Made interactive charts and dashboards for exposure visualization, year-over-year comparisons, and portfolio
insights.
▸ Added map-based features with the Google Maps API for geographic exposure analysis (by country, region, proximity
to shore).
▸ Connected the frontend to backend APIs for dynamic data display, file upload/download flows, and risk data
standardization.
▸ Made sure everything worked well across devices and screen sizes.
Basket Trading Platform - US fintech / asset management product · ~1 year
Stack: JavaScript, React, Redux, Redux Thunk, WebSockets, ChartIQ, Smart Charts, AG-Grid, SCSS, Jest, Enzyme.

▸ Built a SaaS basket trading platform where hedge funds, asset managers, and brokers can build, manage, and trade
custom baskets of stocks as single instruments.
▸ Built portfolio management views for tracking positions, comparing baskets, and looking at performance across asset
classes.
▸ Used WebSockets to push real-time market data updates to charts, tables, and dashboards without page reloads.
 ▸ Integrated ChartIQ and Smart Charts, plus AG-Grid for handling large volumes of live market data.
▸ Built custom data models on the frontend to handle complex, deeply nested financial data.
▸ Optimized rendering on views with frequent real-time updates, cutting down unnecessary re-renders on streaming
data.
▸ Wrote unit tests with Jest and Enzyme; took part in regular code reviews.
Other engagements at Codeit
▸ Fire Emergency Alert System (MVP) - animated real-time platform with live notifications for fire emergencies and
evacuation stats. Stack: React, JavaScript, SCSS, Push Notifications.
▸ Internal Candidate Profile Management System (MVP) - tool for managing candidate profiles with complex field
validation and document/photo uploads. Stack: React, Redux, JavaScript.

Frontend Developer • iDeus Jul 2017 – Jun 2018
On-Site
React UI work on client projects - mostly data-driven interfaces, REST API integration, and reusable component libraries.
Took part in code reviews and regular Agile ceremonies.
Stack: JavaScript, React, Redux, Redux Thunk, SCSS, Jest, Enzyme.

Frontend Web Developer • DOMA group Jun 2016 – Jul 2017
On-Site
Educational Platform - European EdTech
Stack: JavaScript, React, Redux (Thunk/Saga), Webpack, Materialize.
▸ Built UI features for a learning platform with text, video, and audio courses.
▸ Built an admin tool for managing content and a testing/quiz system for end users.
E-commerce Projects - European agencies
Stack: JavaScript, jQuery, HTML, CSS/SCSS, PHP, Gulp, Grunt, Angular, Shopify, WordPress.
▸ Built and maintained frontend for e-commerce sites on Shopify and WordPress - from landing pages to fully custom
themes.
▸ Customized themes and templates per client specs and worked on cross-browser performance.

EDUCATION

Master of Business Administration (MBA) 2014 – 2016
Simon Kuznets Kharkiv National University of Economics · Department of Business Administration
Bachelor's degree, Management 2010 – 2014
Simon Kuznets Kharkiv National University of Economics

CERTIFICATIONS

▸ AI Programming for JavaScript Developers - LinkedIn, 2025
▸ Front-end Developer - 2016

LANGUAGES

Ukrainian - Native · English - Upper-Intermediate · Polish - Conversational