Jan S. - (Freelance) Fullstack Developer

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Berlin, Germany

Experience

Aug 2025 - Present

1 month

(Freelance) Fullstack Developer

Summify.News

Developing an AI-enabled platform that summarizes YouTube channels into daily digests with article and podcast formats.
Built scalable backend in Node.js integrating OpenAI Whisper for transcription and GPT for summarization.
Implemented frontend in React with TypeScript, ensuring responsive design and accessibility.
Set up automated deployment pipelines and CI/CD with Docker & GitHub Actions.

Jun 2024 - Jul 2025

1 year 2 months

(Freelance) Fullstack Developer

Networld GmbH

Developed an AI-powered Business Intelligence Competition Tracker application.
Implemented real-time analytics dashboards with React and D3/Recharts.
Designed microservices in Node.js for scalable data ingestion and processing.
Built an online course platform with user authentication, payments, and video hosting.

Jan 2024 - Jul 2025

1 year 7 months

(Freelance) Fullstack Developer

Anonymous client

Worked on stealth AI medical startup project (cancelled due to lack of funding).
Built HIPAA-compliant infrastructure using AWS and Docker.
Developed clinical data dashboards with React, Next.js, and PostgreSQL.
Integrated medical AI models for patient data analysis and diagnostics.

Jan 2023 - Present

2 years 8 months

Founder

ReactArchitect.AI

Founded and developed SaaS tool for React project visualization and documentation.
Architected platform in NextJS 13 (experimental appDir) with TypeScript and React 18.
Implemented AI server using Node.js (Express) integrated with OpenAI APIs.
Created Electron-based desktop client with OAuth authentication and Stripe billing integration.

Jun 2021 - Dec 2022

1 year 7 months

Fullstack Developer

Fairmas GmbH (Freelance)

Enhanced large-scale Business Intelligence application (>165k LOC) built in React.
Developed new reporting features improving data insights for 150+ employees.
Fixed critical bugs, reducing system downtime and improving stability.
Collaborated with backend team to deliver solutions in ASP.NET C#.

Feb 2021 - May 2021

4 months

Fullstack Developer

Granola Studios GmbH (Freelance)

Built event management web application for Yabal, a 3D virtual game platform.
Designed and implemented microservices with Node.js, Docker, and Kubernetes.
Developed real-time event tracking features to support thousands of concurrent users.
Ensured secure deployment pipelines and optimized container performance.

Mar 2020 - Feb 2022

2 years

React Native Developer

HyperInteractive GmbH

Developed mobile app 'Parti' for theater venue management, published in App Store.
Integrated ticketing, scheduling, and push notifications.
Optimized performance for smooth user experience on iOS and Android.
Worked in an agile team delivering features iteratively.

Jan 2020 - Present

5 years 8 months

Online Teacher

Udemy.com

Created comprehensive 'React Training Course' reaching hundreds of students.
Designed video lessons, coding exercises, and quizzes for effective learning.
Maintained and updated course content with latest React best practices.
Received positive student feedback with an average 4.7/5 rating.

Dec 2018 - Present

6 years 9 months

Founder

Linkbox.io

Founded a startup building bookmarking and link management platform in React & NodeJS.
Won Startup-Weekend Prize for innovative product concept.
Implemented multi-user collaboration features and search optimization.
Scaled platform to handle thousands of users and millions of links.

Jul 2017 - Present

8 years 2 months

Berlin, Germany

Lecturer

Digital Career Institute Berlin (DCI)

Teaching Fullstack React, React Native, NodeJS, HTML, CSS, Linux, and Git.
Mentored hundreds of students transitioning into IT careers.
Developed curriculum materials with focus on practical, project-based learning.
Introduced students to agile methodologies and modern DevOps practices.

Jan 2014 - Aug 2015

1 year 8 months

Erfurt, Germany

Web Developer

PDV-Systeme Erfurt

Developed web clients using Angular, HTML5, and Java Spring REST APIs.
Built Bugzilla analysis system with jQuery for tracking software issues.
Improved system scalability and reduced bug resolution time.
Worked closely with stakeholders to refine requirements.

Sep 2013 - Dec 2013

4 months

BI Developer

Flaconi GmbH

Built Data Warehouses to support online marketing and storage analysis.
Designed ETL processes to handle large datasets efficiently.
Provided actionable insights to marketing teams.
Ensured data quality and reporting accuracy.

May 2013 - Aug 2013

4 months

Freelancer IT Consulting

Delivered consulting services for IT system architecture and web applications.
Advised clients on database design, performance tuning, and cloud migration.
Built small-scale tools for business process automation.

Jan 2013 - Apr 2013

4 months

Leipzig, Germany

Master-Thesis

HHL

Researched adaptation of Business Model Generation framework for internet business models.
Applied framework to selected startup case studies.
Produced academic thesis under supervision of Prof. Dr. Pinkwart.

Jun 2010 - May 2011

1 year

Berlin, Germany

Junior BI Developer

Zalando GmbH

Conceived and developed Data Warehouses for operations, marketing, and customer service.
Implemented ETL processes in Java and Kettle.
Optimized reporting pipelines improving data availability.
Collaborated with cross-functional teams to align data requirements.

Aug 2009 - Feb 2010

7 months

Munich, Germany

Bachelor Thesis

TUM

Developed system for detecting human postures on images.
Implemented algorithms in C++ using OpenCV.
Performed accuracy testing with large datasets.
Presented thesis findings at the Chair of Image Understanding and Knowledge-based Systems.

Aug 2008 - Oct 2008

3 months

Munich, Germany