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Hi, I’m Kristof Kelemen. I’m a full-stack engineer who loves shipping MVPs quickly and learning in the wild through real user feedback. I take ownership of the code I write and enjoy collaborating with backend developers, designers, and stakeholders to turn ideas into reliable software. My background spans fintech and large-scale data pipelines, where I focus on performance, maintainability, and rapid delivery in ambiguous environments. I thrive in teams that value clear communication, thoughtful architecture, and hands-on problem solving.…Hi, I’m Kristof Kelemen. I’m a full-stack engineer who loves shipping MVPs quickly and learning in the wild through real user feedback. I take ownership of the code I write and enjoy collaborating with backend developers, designers, and stakeholders to turn ideas into reliable software. My background spans fintech and large-scale data pipelines, where I focus on performance, maintainability, and rapid delivery in ambiguous environments. I thrive in teams that value clear communication, thoughtful architecture, and hands-on problem solving.

Kristof Kelemen

Full Stack Developer, Front-End Developer, Back-End Developer, +2

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Hi, I’m Kristof Kelemen. I’m a full-stack engineer who loves shipping MVPs quickly and learning in the wild through real user feedback. I take ownership of the code I write and enjoy collaborating with backend developers, designers, and stakeholders to turn ideas into reliable software. My background spans fintech and large-scale data pipelines, where I focus on performance, maintainability, and rapid delivery in ambiguous environments. I thrive in teams that value clear communication, thoughtful architecture, and hands-on problem solving.…Hi, I’m Kristof Kelemen. I’m a full-stack engineer who loves shipping MVPs quickly and learning in the wild through real user feedback. I take ownership of the code I write and enjoy collaborating with backend developers, designers, and stakeholders to turn ideas into reliable software. My background spans fintech and large-scale data pipelines, where I focus on performance, maintainability, and rapid delivery in ambiguous environments. I thrive in teams that value clear communication, thoughtful architecture, and hands-on problem solving.

Available to hire

Hi, I’m Kristof Kelemen. I’m a full-stack engineer who loves shipping MVPs quickly and learning in the wild through real user feedback. I take ownership of the code I write and enjoy collaborating with backend developers, designers, and stakeholders to turn ideas into reliable software.

My background spans fintech and large-scale data pipelines, where I focus on performance, maintainability, and rapid delivery in ambiguous environments. I thrive in teams that value clear communication, thoughtful architecture, and hands-on problem solving.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Intermediate

Work Experience

Frontend Engineer at Pulselive

July 1, 2025 - April 1, 2026

Worked on new features and promotions for a legacy monolithic system, refactored code to modern React and TypeScript, and contributed to delivering an MVP in React Native for another project. Exercised ownership over code and collaborated with backend developers, UI/UX designers, and stakeholders to ensure cohesive delivery.

Big Data Engineer at Telekom Hungary

March 1, 2025 - July 1, 2025

Created a building piece of a large smart failure prevention system using Python, Apache Kafka, PySpark, and MongoDB. System processed 800,000 telemetry data points in 15 minutes across 6 Kafka streams in real time, using stateful micro-batch processing, with data backed up in MongoDB and forwarded to another Kafka stream for further processing.

Frontend Engineer at Medicover

September 1, 2024 - March 1, 2025

Delivered a functional MVP for a CRM system using React. Modernized the codebase with technologies like Vite and TanStack Query, improving build speed by 54%. Collaborated with backend engineers to design efficient endpoints, enhanced performance with caching, and mentored a junior developer to raise code quality. Improved UI/UX with user-centric QoL improvements.

Fullstack Engineer at GiveFront Inc

January 1, 2024 - April 1, 2024

Delivered an MVP of a financial management system in three months to enable early user testing and secure stakeholder approval for further development. Engineered efficient PostgreSQL schemas, enhancing feature integration and reducing query times by ~10%. Strengthened security with endpoint protection and tuned React-Query and Recoil for performance, reducing user-reported lags.

Fullstack Engineer at Frontside LLC

June 1, 2023 - December 1, 2023

Modernized a legacy backend to the latest Node.js, deployed on Ubuntu droplets, improving system reliability and reducing downtime. Maintained CI/CD pipelines, designed and implemented database schemas, and optimized queries by 40%. Built an MVP of an interactive educational game using React and React Native, achieving strong beta engagement and high tester satisfaction.

Frontend Engineer at ITware (Outsourced to Vodafone Germany)

November 1, 2021 - June 1, 2023

Contributed to migrating a legacy codebase to a micro-frontend architecture. Achieved 100% unit and end-to-end test coverage and mentored five junior developers to ensure milestones were met on time.

Fullstack Engineer at Biroda LLC

February 1, 2021 - October 1, 2021

Delivered a highly functional upsell system MVP for a major telecom client, resulting in a 13% upsell revenue increase during pilot testing. Built a Tinder-like mobile app MVP with React Native, facilitating a successful pilot launch.

Frontend Engineer at C3S LLC

January 1, 2019 - January 1, 2021

Improved system performance through caching strategies and refactoring suboptimal components using React. Published a private npm package to visualize satellite orbits and ground stations. Designed and created dashboard views for satellite communication and helped split a monolithic codebase into micro frontends.

Junior Frontend Engineer at Mindtech

January 1, 2018 - January 1, 2019

Gained hands-on experience with React, React Native, JavaScript, and Node across several projects while building an MVP web app for a client.