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Mark twen

@marktwen

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Frontend Lead at TEAM International on Sitecore AI, who cut cold-start page loads by 65% across AI product modules.

Ukraine

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At TEAM International, I lead frontend delivery for Sitecore AI, an AI-powered enterprise CMS and digital experience platform. I guide architecture and implementation across React and Angular applications, and migrated iframe-based micro-frontends to Module Federation, reducing cold-start page load time by 65%.

At Sitecore, I established 85%+ automated test coverage and mentored 10+ engineers. Earlier, I modernized the ExM frontend with a zero-downtime migration to Angular and improved initial load time by 21% through bundle optimization and lazy loading.

I also built a shared design system adopted across 11 applications and introduced Storybook for component development and testing. I focus on scalable frontend architecture, performance, reusable UI patterns, and code quality.

Experience

Work history, roles, and key accomplishments

Current

Frontend Lead

Current

TEAM International

Sep 2025 - Present (1 year 1 month)

Continuing frontend leadership for Sitecore AI product, focusing on architecture, delivery, and team mentorship.

React Angular TypeScript Module Federation TanStack Router Jest React Testing Library Jasmine Karma Performance Optimization Mentorship

Frontend Lead

Sitecore

Mar 2022 - Sep 2025 (3 years 6 months)

Led end-to-end frontend delivery across 3 AI product modules, driving architecture, implementation, and code quality. Migrated micro-frontends to Module Federation, reducing cold-start load time by 65% and established 85%+ test coverage.

React Angular TypeScript Module Federation TanStack Router Jest React Testing Library Jasmine Karma Performance Optimization Mentorship

Senior Frontend Engineer

Sitecore

Nov 2018 - Mar 2022 (3 years 4 months)

Modernized legacy frontend of ExM with zero-downtime migration to Angular for an enterprise email marketing platform. Introduced Storybook and micro-frontend architecture, optimizing bundle composition and reducing initial load time by 21%.

Angular TypeScript Storybook Micro Frontends RPC Performance Optimization Core Web Vitals Lazy Loading

Frontend Engineer

Sitecore

Jan 2012 - Nov 2018 (6 years 10 months)

Built a shared design system adopted across 11 applications and delivered complex Angular and TypeScript features for enterprise CMS products.

Angular TypeScript Design Systems Component Architecture JavaScript HTML CSS

Frontend Developer

Freelance

Sep 2009 - Jan 2012 (2 years 4 months)

Developed responsive, cross-browser websites from UI designs using HTML, CSS, and JavaScript, delivering pixel-perfect implementations for client projects.

HTML CSS JavaScript Responsive Design Cross Browser Development