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I am a Senior JavaScript Engineer specializing in build tooling, developer experience, and platform optimization. I have over six years delivering high-performance web applications, including client projects for Netflix, Marvel, and AMC Entertainment. I am currently developing features and driving platform improvements for a fintech SaaS platform serving 37,000+ UK businesses. My track record includes an 85% reduction in build times and 90% faster test execution.…I am a Senior JavaScript Engineer specializing in build tooling, developer experience, and platform optimization. I have over six years delivering high-performance web applications, including client projects for Netflix, Marvel, and AMC Entertainment. I am currently developing features and driving platform improvements for a fintech SaaS platform serving 37,000+ UK businesses. My track record includes an 85% reduction in build times and 90% faster test execution.

Constantin-Madalin Antonoiu

Web Developer, Programmer, Full Stack Developer, +2

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I am a Senior JavaScript Engineer specializing in build tooling, developer experience, and platform optimization. I have over six years delivering high-performance web applications, including client projects for Netflix, Marvel, and AMC Entertainment. I am currently developing features and driving platform improvements for a fintech SaaS platform serving 37,000+ UK businesses. My track record includes an 85% reduction in build times and 90% faster test execution.…I am a Senior JavaScript Engineer specializing in build tooling, developer experience, and platform optimization. I have over six years delivering high-performance web applications, including client projects for Netflix, Marvel, and AMC Entertainment. I am currently developing features and driving platform improvements for a fintech SaaS platform serving 37,000+ UK businesses. My track record includes an 85% reduction in build times and 90% faster test execution.

Available to hire

I am a Senior JavaScript Engineer specializing in build tooling, developer experience, and platform optimization. I have over six years delivering high-performance web applications, including client projects for Netflix, Marvel, and AMC Entertainment.

I am currently developing features and driving platform improvements for a fintech SaaS platform serving 37,000+ UK businesses. My track record includes an 85% reduction in build times and 90% faster test execution.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Language

English

Fluent

Romanian, Moldavian, Moldovan

Fluent

French

Beginner

German

Beginner

Work Experience

Senior JavaScript Engineer at Crunch

August 1, 2023 - Present

Led platform infrastructure enhancements including Docker and Webpack cache improvements; introduced esbuild and Bun for progressive migration, reducing builds from 17 minutes to under 2 minutes and dependency installs from 11 minutes to under 30 seconds. Reworked testing by migrating Jest to Bun Test and optimising slow tests to maintain full coverage. Delivered features in Agile sprints (e.g., HMRC Making Tax Digital compliance and an internal advertising system). Modernised codebase by deprecating legacy tooling and introducing TypeScript support with esbuild-loader, and regularly participated in security reviews and CI/CD improvements.

Independent Software Engineer at Entrepreneurial Venture

November 1, 2022 - August 1, 2023

Built an automated arbitrage detection and trading platform across 7+ blockchain networks and 25+ exchanges. Developed a Node.js backend with WebSocket for sub-second data delivery and real-time opportunity alerts; implemented secure wallet connections and trades via Ethers.js. Platform leveraged real-time analytics and verifiable on-chain transaction history for opportunistic trading.

Frontend Engineer at Powster Entertainment

August 1, 2021 - November 1, 2022

Developed high-traffic web applications and ticketing platforms for Netflix, Marvel, and AMC Entertainment. Translated complex Figma designs into pixel-perfect, responsive React and Next.js applications within tight deadlines. Modernised internal tooling and refactored legacy Node.js/React code to improve stability and maintainability.

Web Developer at Freelance

August 1, 2019 - July 1, 2021

Delivered tailored web applications for clients using React, Vue.js, and modern frameworks with a strong emphasis on performance optimization and responsive design. Managed end-to-end delivery from requirement gathering to production.