AI Product Builder
Mariusz Smenżyk
I build AI products that get past the demo. Agents that do real work, apps people open every day, and hardware that connects to both. AI-native from day one. Mostly in music and sport.
What I build
Three kinds of products I build.
- 01
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.
- 02
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.
- 03
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.
Sport · Hardware + appsVimo SwimProgrammable swim metronome for swimmers and triathletes, plus apps for swimmers and coaches. In a testing program with Total Immersion coaches in Poland and Spain.
Music · Open sourceMusic metadata toolkit
AI · Open sourceMCP servers
Sport · WearableVimo Swim for Garmin
Sport · CommunityTotal Immersion Cracow
My latest independent project
Meet Vimek. The teammate that runs our back office.
Vimek is a Claude agent I built for the Vimo Swim team. It lives in Slack and reads sales, payment, shipping, ads and analytics data through our own MCP server. When it proposes a change in GitHub Projects, the CRM or the report schedules, it posts a preview, and nothing is written until an allowed teammate clicks Approve.
- read-only MCP tools over company data (Oct 2026)
- 24
- Claude models, one for each job
- 3
- proof of concept and first deploy
- Day 1
- Approve click before any proposed change is written
- 1
How it works. This is a description of the flow, not a real conversation.
- 1
Ask
Someone mentions @Vimek in a Slack thread.
- 2
Read
Vimek answers from live data through read-only MCP tools. Every tool call is logged.
- 3
Propose
For a change in GitHub Projects, the CRM or the schedules, it posts a preview with Approve, Edit and Cancel.
- 4
Approve
Only a teammate on the allowed list can approve. Scheduled runs never propose changes.
- 5
Write
The change runs once and is recorded with the name of the person who approved it.
Slack thread to task
Mention @Vimek in a thread and it proposes a GitHub Projects task, checks for duplicates and can move cards between columns, each after Approve.
Scheduled reports
It can post where the sales funnel stands and the top 3 priorities on weekday mornings. The team adds new schedules by asking in Slack, and each one needs Approve.
CRM updates
"Mark this lead as lost" becomes a before and after preview. After Approve, the change lands on the lead's timeline with the name of who approved it.
Posted without Approve
Slack replies and scheduled reports are posted directly. The MCP server has one write tool, for release notes, and it stays off unless the API key allows writes.
Safe by design
A read-only database role for the MCP server, an audit log for every tool call, and the token cost of every run logged.
Open source
Built in the open.
MCP servers, Claude skills, music tech tools and small experiments, all public on GitHub. Music tech tools live under MusicTech Lab, my own tools and experiments under my account. Six of them below.
- trello-mcpTrello boards, lists and cards from Claude Code.Python
- mtl-metadata-mcpRead and write tags in MP3, FLAC and OGG files.Python
- ddex-validateClaude skill that validates DDEX ERN XML against official schemas.
- mtl-ddexvalidatorWeb app that validates DDEX XML files against many schema versions.Django
- mtl-c2pa-abletonMax for Live device that shows C2PA info inside Ableton.Python
- arduino-midi-abletonArduino MIDI controller with two buttons for Ableton Live.C++
How I work
Simple rules, kept.
I am not taking new projects. I am open for consultations, and they follow the same rules as the products I built: business first, one clear question, a written answer.
- What a consultation covers
AI strategy: where AI makes sense in your business and where it does not. Architecture and code review: what to fix first. MVP and launch plan: what to build first and what to leave out.
- How it works
Email me one clear question. I reply within two working days. If a call helps, you book a slot in my calendar. After the call you get a written summary with next steps.
- Where the advice comes from
Twenty years of building products end to end, from the first call to the app store or the device. Today I build my own products, Vimo Swim and Vimek, with the same tools I would recommend to you.
Async by default
Fewer meetings. More Loom.
I work async. Instead of another call, you get a short video: a demo of what shipped, a decision explained on screen, or a review you can watch at 2x speed. You reply when it suits you, and nothing gets lost in a meeting nobody wrote down.
Numbers from my Loom library
- Loom videos recorded
- 1,400+
- Products and client projects run on video updates
- 17
- Videos in a single product
- 176
- Working async since
- 2021
Demo after every release
Each release comes with a short walkthrough, so you see the real thing, not a status line.
Decisions on screen
Trade-offs and options explained with the code or design open, ready to forward to your team.
Reviews you can replay
Code, design and data reviews recorded once and watched by everyone, in any time zone.
Onboarding that stays
Every video lands in a shared library, so new people catch up without a single meeting.
Polymath
Engineer, founder, maker, TI coach.
I'm a polymath. I don't fit in one box, and that is the point. Each role feeds the others: the coach finds the real problem, the engineer builds the fix, the founder gets it to people.
- 01
Engineer
Twenty years of writing software. Today most of it is written with AI agents that I direct, review and ship.
- 02
Founder
Sizeof, Bravelab, MusicTech Lab and now Vimo Swim. I know what a product needs besides code.
- 03
Hardware maker
Embedded Rust on nRF52, BLE, OLED and my own boards, from the first breadboard to a production batch.
- 04
Swim tech & sports data
Wearables, tempo trainers and training data for swimmers and coaches. Vimo Swim is where I put it all together.
- 05
Swim coach
Total Immersion coach in Kraków. The pool is where my sport products meet real users first.
Credentials
- Wearable Technologies and Sports Analytics University of Michigan · CourseraIn progress
- SwimTech Coach (STC) Elite Swim Performance Academy2026
- Design Thinking In Practice We are very2020
- Postgraduate Studies in IT Business Management AGH University of Kraków2019
- Team Kanban Practitioner Lean Kanban University2019
- Management 3.0 Foundation Management 3.02018
Track record
Twenty years of shipping. Now with AI in every step.
I founded two software companies, served as CTO, and built products for labels, tour operators and startups. Today I work with AI tools and ship alone what used to need a team. Most of my products live in music and sport, where I know the users best.
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.
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 proved to be 100% reliable partner. Extreme engagement in the project followed by professional work, great communication and dependability sums up Mariusz traits. Acute eye for detail, top notch technologies used is a standard. Not to mention first class relationship management. I had several ongoing projects which Mariusz will take a strong part in.
Writing
Notes from the workbench.
What I learn while building, written up so the next person ships faster.
- 01Building a YouTube Video Research Pipeline with Whisper and ClaudeFeb 2026
- 02Automating Google Docs with Claude Code: Build a CLI That Pulls, Edits, and PushesFeb 2026
- 03Building a Garmin Connect IQ App in Monkey C: Lessons from a BLE Remote ControlFeb 2026
- 04Smart Home on a Budget: BLE Window Sensors with Two Pico Ws and MicroPythonFeb 2026
Ask a question
Ask me anything.
I'm not taking new projects right now, but I'm open for consultations on AI strategy, architecture and code review, or an MVP and launch plan. Email me your question. I reply within two working days, and if a call helps, you can book a slot in my calendar.