Hello, I'm Bartek
Full-Stack Developer
specializing in Mobile Development
Based in Netherlands
I enjoy building practical, minimalistic,
and easy to use apps and websites
Work Experience
My professional journey in full-stack development and Mobile Development
Quill
Backend & Frontend Developer
August 2025 - Present
Remote
- •Built comprehensive backend infrastructure using Firebase Realtime Database for live collaboration and Firestore for persistent data storage
- •Developed real-time collaboration features allowing Unity teams to lock assets, preventing conflicting changes during development
- •Implemented commenting and notes system that enables developers to write feedback directly in Unity with instant synchronization across all team members
- •Integrated Sentry for error tracking and PostHog for analytics, ensuring robust monitoring and valuable user insights
- •Created modern Next.js frontend providing responsive interface for managing collaboration workflows
Next.jsTypeScriptNode.jsFirebaseFirestoreFirebase FunctionsSentryPostHogUnity Integration
TheWidlarzGroup
React Native Developer
May 2025 - Present
Kraków, Poland (Hybrid)
- •Implemented and maintained native modules for React Native, focusing on cross-platform video functionalities
- •Maintained and extended the react-native-video library, leading development of its native implementations in Swift (iOS) and Kotlin (Android)
- •Designed and built a server for stream-downloader, a library enabling offline video playback
- •Developed features in stream-downloader to support downloading and offline playback of HLS, DASH, MP4, and DRM-protected video content
React NativeSwiftKotlinTypeScriptHLSDASHVideo StreamingDRM
Outlier
AI Developer (Freelance AI Trainer)
Apr 2025 - Aug 2025
United States (Remote)
- •Work as a freelance AI trainer, helping improve how AI understands and writes code
- •Write effective prompts for AI systems and optimize their performance
- •Review AI-generated code as well as code from other contributors for quality and accuracy
- •Rate, fix, and improve code when needed to maintain high standards
- •Contribute to training datasets that enhance AI model capabilities in software development
JavaScriptTypeScriptReact.jsPythonCode ReviewAI TrainingPrompt Engineering
InnoBee
Product Developer (Frontend Developer)
Mar 2025 - Jun 2025
Netherlands (Remote)
- •Contributed to developing and enhancing web applications using modern technologies like Next.js, React, TypeScript, and Tailwind CSS
- •Focused on building responsive user interfaces and collaborating with the team to deliver clean, scalable solutions
- •Stayed current with frontend trends and implemented best practices for modern web development
- •Worked on innovation management platform features to improve user experience and functionality
Next.jsReactTypeScriptTailwind CSSJavaScriptHTML5CSS3
Freelance Projects
Full Stack Developer
2023 - Present
Remote
- •Designed and developed custom web applications including CleanupHub, Shared Alarm, and Trapla
- •Created modern, responsive user interfaces with focus on exceptional user experience
- •Built full-stack solutions using React, Next.js, tRPC, and various database technologies
- •Delivered end-to-end solutions from initial concept to deployment and maintenance
- •Managed multiple client projects simultaneously while maintaining high quality standards
ReactNext.jsTypeScriptTailwind CSSPrismatRPCPostgreSQLFigma
Technologies I Work With
Next.jsFull-stack framework for React applications with server-side rendering and static generation
React & React NativeBuilding interactive user interfaces for web and mobile applications
TypeScriptType-safe JavaScript that scales for reliable enterprise applications
Tailwind CSSUtility-first CSS framework for rapid UI development
SwiftNative iOS development for performant mobile applications
KotlinModern programming language for Android and cross-platform development
FirebaseBackend platform with auth, Realtime Database, NoSQL DB - Firestore, and Cloud Functions
PostgreSQLAdvanced open-source relational database for scalable applications
My Projects
Quill
August 2025
Backend & Frontend Development
Next.js, TypeScript, Node.js, Firebase
A real-time collaboration tool for Unity game development teams.
Shared-Alarm
2025
Development & UI / UX Design
React Native (Expo), Supabase, Native Wind
A collaborative alarm app that lets you share and sync alarms with friends and family.
Zabrze-Franciszek
2024
Development & UI / UX Design
Next.js & Typescript, PostgreSQL, NextAuth
A website which I created for my church parish.