I build products
Mariusz Smenżyk
Agents, apps and hardware that get past the demo. Today I build for sport, where I know the users best. Above all for swimming, my great love.
What I build
Three kinds of products I build.
AI agents and automation
Assistants, pipelines and MCP servers on Claude and Python. They turn data, video and documents into answers and actions, inside the tools a team already uses.
Web platforms and apps
Web platforms in Nuxt and Django, mobile apps in Flutter. From the first screen to launch, with staging, tests, analytics and crash reports from the start.
Hardware and wearables
Embedded Rust on nRF52, BLE and ANT+, Garmin Connect IQ. Prototypes you can hold, strap on and test in the water.
Selected work
Things I build and run.
Open source
Built in the open.
MCP servers, SDKs and small experiments, all public on GitHub. Six of them below, the rest in the full catalogue.
Track record
Twenty years of shipping. Now with AI in every step.
I founded two software companies and held executive roles as CEO, CTO and founder. I built products for labels, tour operators and startups. I work with AI tools and ship alone what used to need a team. Today I build for sport, where I know the users best. Music, travel, e-commerce and loyalty came before.
I am continually impressed by how Mariusz shows up as both a strategic planner and a hands-on builder. He is especially good at helping to manage my "feature creep" by grounding big ideas into clear, achievable initiatives without killing momentum or curiosity. Mariusz can go from early research and prototyping to production-ready systems. What stands out most is his ability to roll up his sleeves and find solutions in situations where there aren't obvious answers. I appreciate the way he experiments, learns quickly, and delivers, in addition to the strategic support he provides.
Mariusz is a wonderful human-being and through his values, created and leads a top-tier product agency with his colleagues at Bravelabs. As a product advisor I had the pleasure of working with Bravelabs team hire the founding product team for an early stage venture. Through the hiring and client management process the Bravelabs team ran a professional and robust process resulting in an excellent team. The outcome of whose work resulted in a jaw dropping Product Concept the venture could take to investors. I recommend Bravelabs if you are looking for a professional partner for product design and development.
Marius and his team built us an incredibly useful piece of software and delivered on budget - doing a thoroughly professional and diligent job throughout the whole process.
Mariusz and the team at Bravelab are absolutely fantastic at working with non-tech founders, they supported the development of the Wundr platform and I would highly recommend them to anyone commencing a complex MVP build. Mariusz knows his space well and goes beyond the call of duty time and time again! Many thanks Mariusz a pleasure working with you and the team.
Working with Mariusz and MusicTech Lab has been a pleasure. Mariusz provided us with helpful regular updates across the development process, and went above and beyond in delivering additional features and ideas. His ability to problem-solve and resolve any issues swiftly helped deliver an excellent final product.
I would call what Mariusz is and does as a ‘Solution Finder’. (Not to be confused with just a problem solver.) He and his team can bring together an idea and then execute it into reality. We have worked with him on several projects and I can highly recommend him and his work. I am impressed with his abilities and have already recommended him to friends knowing he can guide them and create from idea to App. - *****5 Stars
As a business partner, Mariusz is a very open mind person. He believes in innovation culture and is always ready to listen to ideas and opinions from others. His decisions are based on reliable information and considering all facts possible to reach every goal successfully.
It is hard to find someone who is as well respected as Mariusz is, I can't even call him my boss he is a friend. He approaches every task with a can-do attitude, goes out of his way to help everyone, and has a great sense of purpose and passion for his business. Mariusz is the rare kind of individual that puts your needs before his. I am humbled to work for such an individual, Mariusz earns my highest recommendation.
Writing
Notes from the logbook.
What I learn while building, written up so the next person ships faster.
- 01My Claude Code sessions now say which project they areFour Claude Code sessions, one Ping sound, no idea which one needed me. A small hook script now speaks a short word per project, queues the voices and has a mute switch for meetings.Nov 2026 · 4 min read
- 02A share card for every page, checked by the build90 of 116 pages on a Nuxt site shared to LinkedIn with no image at all. Here is how we render a card per page at build time with nuxt-og-image and Satori, and make the build fail when a card goes wrong.Nov 2026 · 5 min read
- 03I tested the AI reverse engineering hype. The useful part was defenceA list of 46 'an AI agent rebuilt this closed app' cases looked like a toolbox. The benchmarks on the same page show no real gain, and two of the three tools I tried do not run on a Mac. One defensive check was worth keeping.Nov 2026 · 5 min read
- 04Handoff notes between two Macs: the terminal tells me what the other one leftSome work done on one Mac needs a step on the other. Now Claude leaves a note in git, and the next terminal on the other Mac shows it as a short checklist I can start with one command.Nov 2026 · 4 min read
Say hello
Let's talk.
This is not a sales page. If something here made you think of your own work, write to me. The best conversations leave both sides with a new idea. I reply within two working days.