Apps Portfolio

Portfolio

Works imagined, designed and built by Marco.

After over two decades as a software engineer, I made a conscious pivot into product design. I had grown weary of chasing every new framework in an industry that never sits still. I wanted to focus on creating intuitive experiences, not just clean code. So, I shifted toward UX and product development. Until something pulled me back in.

That something was AI.

With the rise of AI-assisted coding, I've found a way to merge my UX expertise with my engineering roots. The result? I can now build high-quality, fully functional software in a fraction of the time it used to take and enjoy every minute of it.

I know I said I didn't have a portfolio because I don't believe in them anymore but… here we are. This is my portfolio. No endless rambling, no showcasing work other people in my team did and no having to wonder "How much of this did he actually do himself? By whoever is looking at this.

This portfolio is a living collection of real-world projects I've built using AI tools, my full-stack SWE thinking skill set AND my UX skills. These aren't static mockups or throwaway prototypes. They're production-ready apps, designed, developed, and shipped by me. If you want to see for yourself that these are the real deal and not just a shiny demo, feel free to contact me and I will give you access so you can see for yourself!

So dive in. This is what happens when UX meets AI assisted development and velocity meets vision. This is what happens when you hire a designer who can code his vision into polished, high-fidelity output.

My AI Diary (working title)

I built My AI Diary to completely rethink how we journal in the age of AI. Most of us have thoughts worth capturing, but typing them out every day feels like a chore. With MyAIJournal, you just speak naturally, and the AI turns your raw voice into a beautifully written journal entry that still sounds like you, just a bit more polished.

The app focuses on simplicity and privacy. You can record entries on the go, and the AI takes care of the rest: transcription, enhancement, tagging, sentiment analysis, and even smart summaries over time. You can search past entries, attach photos, export to PDF, and switch between local or encrypted cloud storage whenever you want. Everything is encrypted by default using your login password. Bullet proof privacy and security.

I designed this for people like me: those who want to reflect and grow, but don't always have the time or energy to write everything down. This is journaling, redesigned for the way we live now.

This entire app was designed and built by me using the Augment Code agent.

My AI Diary Mobile Screenshot 1
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Calorie Counter

The most frictionless food intake logger ever created. I built this app for myself and then realized that a lot of people besides myself will probably really love to use this as well. This is not your average calorie counter app. It features entry through barcode scanning, text entry, voice entry and even pictures of the food you are eating.

This app uses the OpenAI API to process your entries into caloric values as well as the three macronutrients: carbohydrates, fat and protein. You can also enter offset values for workouts and other exercise that will be subtracted from the net calorie intake value for the day.

You can set your own custom goals, export your data in CSV format, edit past days in case you forgot something and look at comprehensive graphs showing your food intake over time.

Calorie Counter Screenshot 1
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Thought2Tweet

I built Thought2Tweet to solve a problem every content creator faces: turning fleeting thoughts into engaging social media posts. We all have brilliant ideas throughout the day, but by the time we sit down to write, the magic is gone. With Thought2Tweet, you simply tap record, speak your thoughts naturally, and AI transforms your voice into viral-ready content that captures your authentic voice while optimizing for maximum engagement.

The app streamlines the entire content creation process from thought to post. You record your ideas anywhere, and the AI handles transcription using OpenAI's Whisper, then generates both short-form tweets and long-form content in your choice of style: Viral, Spicy, Neutral, Professional, or LinkedIn. The interface is mobile-first with a sleek dark design, featuring smart wake-lock technology to prevent interruptions during recording, one-tap sharing to any platform, and a complete history of all your generated content stored securely in IndexedDB.

I designed this for busy creators, entrepreneurs, and thought leaders who have valuable insights but struggle with the friction of traditional content creation. Instead of staring at a blank screen wondering how to phrase something, you just speak naturally and let AI handle the optimization. This is content creation, redesigned for the way we think and share ideas today.

This entire app was designed and built by me using the Augment Code agent.

Thought2Tweet Screenshot 1
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Thought2Tweet Screenshot 4

Audio Visualizer Suite

Audio Visualizer Suite is a powerful, all-in-one tool for creating captivating video visualizations of your music. Whether you're a musician, content creator, podcaster, or sound designer, this suite enables you to generate beautiful, dynamic visuals that pulse and react in real time to your audio.

Choose from a wide variety of spectrum analyzers, waveform renderers, and intricate audio-reactive animations. Each visualization type is fully customizable, allowing you to tailor the look and feel to match your artistic vision or brand identity.

You can layer your visualizer over a static image, a seamless looping video, or elevate it further by pairing it with one of the many built-in high-performance GL shaders. These shaders span everything from abstract particle systems to elegant organic forms—each one designed to bring your audio to life in visually compelling ways.

Whether you're looking to publish your tracks on platforms like YouTube, Instagram, TikTok, or use them in VJing, live streams, or digital art installations, Audio Visualizer Suite offers an effortless way to create polished, professional-grade videos that keep viewers engaged.

No need for complex editing software. Just load your track, select your style, and render. It's your music, visualized beautifully.

🎵 Open Source: Perfect for musicians, content creators, and developers interested in audio visualization technology!

Audio Visualizer Screenshot 1
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Social Media Downloader

I built this Social Media Downloader to solve a simple but persistent problem: saving content from platforms like YouTube, Instagram, TikTok, and Twitter without jumping through hoops or dealing with sketchy websites. Whether it's a tutorial you want to watch offline, a funny video to share later, or content for a presentation, this tool handles it all in one clean interface.

The app supports multiple formats and quality options, works with dozens of platforms through yt-dlp integration, and provides a simple drag-and-drop interface for batch downloads. Everything runs locally on your machine, so your data stays private, and there are no file size limits or subscription fees.

I designed this for content creators, researchers, and anyone who needs reliable access to social media content without the usual friction. It's the tool I wish existed when I was constantly bookmarking videos I'd never watch again.

Social Media Downloader Interface

🚀 Open Source: Fork it, contribute, or use it as a starting point for your own projects!

Jumbotron Simulator

I created this Jumbotron Simulator as a fun way to experience the thrill of seeing your name in lights at a major sporting event. Whether you're celebrating a birthday, anniversary, or just want to feel like a VIP for a moment, this tool lets you customize messages and see them displayed on realistic stadium jumbotrons.

The simulator features multiple stadium templates, customizable text and colors, realistic LED display effects, and the ability to save or share your creations. It's built with HTML5 Canvas for smooth animations and responsive design that works on any device.

I built this for sports fans, event planners, and anyone who wants to create memorable digital experiences. Sometimes the best projects are the ones that just make people smile.

Jumbotron Simulator Interface

🎯 Open Source: Perfect for learning HTML5 Canvas, animations, and interactive web graphics!

The Last Weather App

I built "The Last Weather App" because I was tired of weather apps that either overwhelmed me with data I didn't need or failed to give me the essential information I actually wanted. This app focuses on what matters: current conditions, hourly forecasts, and a clean, distraction-free interface that gets you the information you need in seconds.

The app uses multiple weather APIs for accuracy, provides location-based forecasts with GPS integration, and features a minimalist design that prioritizes readability and speed. No ads, no clutter, no unnecessary features—just reliable weather information when you need it.

I designed this for people who want weather information, not weather entertainment. Sometimes the best app is the one that does one thing exceptionally well.

Weather App Screenshot 1
Weather App Screenshot 2

💡 Pro tip: Use "Add to Home Screen" on your mobile device to install it as a native app for the best experience!

Color Clocka clock design I created in 1991, brought to life with AI coding

Back in 1991, I designed a unique clock concept where time was represented through color gradients instead of traditional numbers. Fast-forward to 2024, and I brought this vintage idea to life using modern web technologies and AI-assisted coding. The result is a mesmerizing digital timepiece that displays the current time through smooth, flowing color transitions.

The clock uses HTML5 Canvas to create fluid color animations, with each hour, minute, and second mapped to specific hue, saturation, and brightness values. The interface is hypnotic and meditative, turning timekeeping into a visual art experience. It's perfect for ambient displays, meditation spaces, or anyone who appreciates the intersection of time and color.

This project represents the beautiful marriage of vintage design thinking and modern AI-powered development. Sometimes the best innovations come from revisiting old ideas with new tools.

Real TimeDemo
12h24h
Concept © 1991-2025 Marco van Hylckama Vlieg
Live Color Clock

Experience time as moving color dials. Each segment transitions as hours pass, creating a unique visual representation of the current moment.

Persona Personifieda Custom GPT to help you work with personas

I created Persona Personified to solve a common problem in marketing and product development: creating authentic, detailed user personas that actually guide decision-making. Most persona exercises result in generic profiles that sit in a drawer. This Custom GPT transforms the process by helping you develop rich, nuanced personas through guided conversations and research-backed methodologies.

The GPT walks you through persona development step-by-step, asks probing questions to uncover deeper insights, helps you identify pain points and motivations, and generates comprehensive persona documents that your team can actually use. It's trained on best practices from UX research, marketing psychology, and behavioral science.

I designed this for product managers, marketers, UX researchers, and entrepreneurs who want to build products and campaigns that truly resonate with their audience. Understanding your users isn't just good practice—it's the foundation of everything that works.

LLM assisted writing on Medium

I've been exploring the intersection of human creativity and AI assistance through a series of articles on Medium. These pieces dive deep into how Large Language Models can enhance rather than replace human writing, covering everything from ideation and research to editing and optimization.

My articles explore practical workflows for content creators, the ethics of AI-assisted writing, techniques for maintaining authentic voice while leveraging AI capabilities, and real-world case studies of successful human-AI collaboration. Each piece is itself an example of thoughtful AI integration—enhanced by technology but driven by human insight and experience.

I write for fellow creators, marketers, and anyone curious about the future of content creation. The goal isn't to promote AI as a replacement for human creativity, but to explore how these tools can amplify our natural abilities and help us create better work, faster.

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