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NewA 9-month company budget from six data sources in one hour

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Logbook

Everything I build and write, in one place. Projects I run or ran, and the notes I write while building, so the next person ships faster.

  • 89entries
  • 13projects
  • 56articles
  • 17years on record

2026

34 entries

  1. 2023 to 2026 · Past life

    Music & Sport

    Founder of MusicTech Lab · Co-founder of MusicTech Poland · CTO at Ambistream

    A software company for the music industry. We built royalty analytics, AI content platforms and tools for labels and distributors, and published open source tools for music metadata.

    What I took with me Data standards are where products break. And MCP servers, which I first built for music data, are now how I connect AI to everything.

    PythonDjangoNuxtClaudeMCPDDEXC2PAAbleton Live
    musictechlab.io MusicTech Lab on GitHub DDEX validator SmartFeed Media
  2. Wearable Technologies and Sports AnalyticsUniversity of Michigan · Coursera SportCertificate
  3. A 9-month company budget from six data sources in one hourI pulled data from three bank accounts, the invoicing system, the finance ledger and email, and turned it into a 9-month cash budget in about an hour. A job like this used to take me days. The difference was the tools I had built before. AI & codeArticle
  4. Is this email address live? Ask the mail server, then fix it in CloudflareI added two aliases on my domain with Cloudflare Email Routing and Gmail Send mail as. The useful part was checking an address with one SMTP command before and after, and two Gmail login errors that look the same but are not. AI & codeArticle
  5. Getting paid in USD as a Polish sole trader: Wise, wFirma and one morningI moved a US client from my limited company to my own sole trader business in one morning. Wise verification, US account details on a Polish invoice, and the wFirma traps I hit on the way. OtherArticle
  6. Cleaning 199 GB of duplicates out of Google Photos from inside ChromeGoogle Photos has no API to delete photos, so Claude did it in my browser: fingerprint thumbnails in the page, bin RAW files that have a JPEG twin, check every selection against Google's own counter. AI & codeArticle
  7. A KSeF MCP server in an afternoon, for three companies at onceI built a small MCP server for KSeF, the Polish e-invoicing system, so Claude can list and download invoices for my three companies. The login flow is short, and the one trap is that every token belongs to exactly one company. AI & codeArticle
  8. Merch shirts on a 3D dress form, built headless in BlenderIn one afternoon, a client's flat Shopify mockups became shirts you can turn round in the browser. The hard part was not the 3D. It was a sleeve that looked like a cape. AI & codeArticle
  9. What is inside a Garmin swim FIT fileI decoded 1,234 of my own Garmin FIT files to see what a swim dashboard can show. Pool files carry every length, open water carries GPS and water temperature, and two big undocumented messages turned out not to be raw IMU data. SportArticle
  10. Finding Instagram reels in years of video, fully local on a MacI built a small Claude Code skill that turns a Google Photos Takeout into a searchable list of scenes, using ffmpeg, MLX Whisper and a vision model in LM Studio. The surprise was not the AI part, it was Whisper inventing speech on silent clips. AI & codeArticle
  11. Moving 305 GitHub repos from an org to my own accountI moved almost every repo out of an org into my personal account, because I will look after them from now on. The only surprise was a redirect that looked like a name clash. AI & codeArticle
  12. Swimming testimonials and the tempo math behind themOn vimoswim.com the coach quotes swim across a pool. Stop a swimmer and the quote opens. Both the pool and the tempo calculator behind it run live here. SportArticle
  13. A swim tech coaching course I finished on a planeI took the SwimTech Coach (STC) Certification on Udemy during a flight. It promises data-driven swim coaching with wearables. It stays very basic and repeats itself, and I learned nothing new. SportArticle
  14. Testing a swim metronome with a Mac microphoneA tester heard Vimo Swim beep 33% slower than set. We fixed the firmware in an afternoon, then built one command that records the beeps with the Mac mic and checks the tempo to 1%. HardwareArticle
  15. Analytics showed nothing although cookies were acceptedGA4 on mtl.dev stayed empty after I accepted my own cookie banner. The banner stored the choice but never told gtag about it on the next page load, so every hit went out as a denied ping. One consent update on mount fixed it. AI & codeArticle
  16. A product render of Vimo Swim in one evening with Blender and MCPOn October 25 I pointed Claude Code at Blender through the MCP add-on, gave it the CAD files of the Vimo Swim device and a brief, and by midnight the exploded-view animation was on vimoswim.com. What the workflow looked like, where it measured wrong, and the one rule that made it reproducible. AI & codeArticle
  17. Two Macs, one Claude Code setup: skills as plugins, not symlinksI moved 36 Claude Code skills out of 17 tiny repos and a pile of symlinks into two plugins, one public and one private, with a make pull on the other machine. Here is what changed and why. AI & codeArticle
  18. Garmin Connect Developer Program: From Application to First Webhook in One AfternoonGarmin reopened its Connect Developer Program with a free Starter tier. Here is the exact path we took for Vimo Swim: application, OAuth2 PKCE, push endpoints, and the two things that are easy to get wrong. SportArticle
  19. From the first Garmin swim to a details page in one eveningGarmin Connect started pushing swims to Vimo Swim on October 29. The summary showed up on the site within minutes, the laps and heart rate took one more evening. What made it quick: store every push raw before you parse anything. SportArticle
  20. Librus BotSchool messages from Librus Synergia go to a private family Slack channel, so nobody has to log in to the school app to read them. OtherProject
  21. VimekA Claude agent for the Vimo Swim team. It lives in Slack, reads our company data through our own MCP server, and proposes changes that a teammate approves. AI & codeProject
  22. One MCP Server, Two Auth Stories: Claude Code vs. Claude DesktopWhy adding Claude Desktop support to an internal MCP server meant building real OAuth 2.1, even though Claude Code was happy with a static token. AI & codeArticle
  23. Codemagic MCP Server: Trigger Mobile CI Builds from Claude CodeI open-sourced mcp-codemagic, an MCP server that brings Codemagic CI/CD into Claude Code. List apps, trigger builds, check status, and cancel runs without leaving your terminal. AI & codeArticle
  24. SwimTech Coach (STC)Elite Swim Performance Academy SportCertificate
  25. C2PA in Ableton: Making AI Music Provenance Visible Inside Your DAWIn May 2026 I shipped an MCP for reading C2PA manifests in music. This post is the follow-up: the same reader, now inside Ableton Live as an open-source Max for Live device. MusicArticle
  26. C2PA in Music: A Claude MCP for Reading Content ProvenanceC2PA is the open standard for content provenance, and it just landed in music files. I open-sourced an MCP server so you can read these manifests inside Claude Code. MusicArticle
  27. I taught Claude to sell my old diving gear on OLXMy 11-year-old son and I had 50 used items to sell on OLX and a spreadsheet that tracked who owns what, who gets paid what, and at what price. So I built an MCP server and let Claude do the listings. AI & codeArticle
  28. Building a YouTube Video Research Pipeline with Whisper and ClaudeHow I built a CLI tool that downloads YouTube videos, transcribes them with Whisper, and generates structured market intelligence using Claude — all with one command. AI & codeArticle
  29. Automating Google Docs with Claude Code: Build a CLI That Pulls, Edits, and PushesHow I built a Python CLI tool that lets Claude Code read and write Google Docs directly — editing DOCX files programmatically, fixing typos, styling tables, and reading comments, all from the terminal. AI & codeArticle
  30. Building a Garmin Connect IQ App in Monkey C: Lessons from a BLE Remote ControlWhat I learned building a Garmin watch app that controls a swim metronome over BLE — from GATT command queues to manual ASCII parsing in a language with no regex. SportArticle
  31. Smart Home on a Budget: BLE Window Sensors with Two Pico Ws and MicroPythonHow I built a wireless window monitoring system using two Raspberry Pi Pico Ws, reed switches, and BLE — with async MicroPython, aioble, and zero cloud dependencies. HardwareArticle
  32. Mirroring a Wearable OLED Display to a Projector for Live DemosHow to stream a tiny OLED screen from an embedded device to a laptop and projector in real-time using UART and Python. A practical guide for hardware demos and presentations. HardwareArticle
  33. Learning Embedded Rust: A C/Python Developer's Rosetta StoneA practical guide for C and Python developers transitioning to embedded Rust. Side-by-side comparisons of ownership, error handling, pattern matching, and more — mapped to concepts you already know. HardwareArticle
  34. NFC Tag Emulation on nRF52840 with Rust — No SDK RequiredHow to turn a bare nRF52840 into an NFC Type 2 Tag using only PAC registers and Embassy async, running alongside BLE SoftDevice. A practical walkthrough with full code. HardwareArticle

2025

11 entries

  1. Tempus Metronome and GetSongBPM APIWhat BPM really means and how I integrated the GetSongBPM API into Tempus Metronome using Flutter to let users look up song tempos instantly. MusicArticle
  2. Verified Human Cert MCP Server: Prove Your Music Is Human-Made, Right from the TerminalI built an MCP server that queries the Verified Human Cert registry. Verify human-made music certifications by ISRC, artist, track, or cert number directly from Claude Code. AI & codeArticle
  3. Querying Bandcamp Revenue Reports with Natural Language — Meet mtl-bandcamp-mcpAn MCP server that turns Bandcamp CSV exports into queryable dashboards. Ask about artist splits, fee breakdowns, and top sellers — no spreadsheet needed. MusicArticle
  4. mtl-metadata-mcp: Open Source Audio Metadata Embedding for Claude CodeI built an open source MCP server that reads and writes metadata tags in MP3, FLAC, and OGG files directly from Claude Code. Here is how it works. MusicArticle
  5. SignNow MCP Server: E-Signatures Straight from Claude CodeI open-sourced an MCP server that brings SignNow e-signatures into Claude Code. Upload documents, send signing invites, track status, and download signed PDFs — all without leaving your terminal. AI & codeArticle
  6. 1,200 Looms Later: How Async Video Became My Development SuperpowerI've recorded 1,212 Loom videos over 5 years. Here's how async video transformed the way I demo, communicate with clients, and document decisions as a founder and developer. OtherArticle
  7. Building a Claude Skill for DDEX Validation: Automate Music Metadata Checks with AIA step-by-step guide to creating a Claude Code skill that validates DDEX ERN XML files against official schemas - catching metadata errors before they reach distributors. MusicArticle
  8. Integrating SignNow E-Signatures into Your Django ApplicationA practical guide to adding e-signatures to your Django app with the SignNow REST API: OAuth2 auth, document uploads, Celery signing workflows, and webhooks. AI & codeArticle
  9. How to Transcribe Video to Text Using OpenAI WhisperA practical guide to the video → mp3 → text pipeline using OpenAI Whisper. Free, local transcription for interviews, podcasts, and meetings. AI & codeArticle
  10. How to Create a Watch Face App for Garmin WatchLearn how to build a custom Garmin watch face using the Connect IQ SDK and Monkey C. A step-by-step tutorial based on my BeatBuddy watch face experiment. SportArticle
  11. BeatBuddy Replay: Video Analysis App ChallengesA deep-dive into how I built a Flutter video analysis app for swimmers. From MVP architecture to cross-platform challenges - my lessons from two weeks of development. SportArticle

2024

10 entries

  1. Notion Backup Tool Built in 3 Days with PythonHow my team and I built an automated Notion-to-Markdown sync tool in 3 days, why we left Notion, and why I open-sourced the solution. AI & codeArticle
  2. DIY MIDI Controller for Ableton with ArduinoBuild a physical MIDI volume controller for Ableton Live using Arduino Leonardo. Covers hardware setup, MIDI protocol, and USB communication. HardwareArticle
  3. Extracting Data from Ableton .als and .asd FilesA deep dive into parsing Ableton Live project files. Learn what metadata hides inside .als and .asd files and how I extract it with Python. MusicArticle
  4. AI Song Structure Analysis: Intro, Verse, ChorusA technical look at automatic song structure detection using AI and signal processing. Identify song sections with my tool, MTL Audio Locators. MusicArticle
  5. SmartFeed MediaAI-curated newsletters for the music industry. The platform reads trade news every day, scores each article against what a team cares about, and sends a short newsletter with summaries of the top stories. Built at MusicTech Lab for a Polish collective rights organisation. MusicProject
  6. Spotify PedalBoardOpen source GUI for real-time audio effects, built on Spotify's Pedalboard library. Written in Python and published by MusicTech Lab. MusicProject
  7. Connecting Your Max for Live Device to a Cloud APISend song structure data from Ableton Live to a cloud API. Build a complete DAW-to-database pipeline with real-time visualization. MusicArticle
  8. Export Ableton Locators to JSON via Max for LiveBuild a Max for Live device that exports arrangement locators and BPM to JSON, ready for external tools and AI music analysis pipelines. MusicArticle
  9. MusicTech PolandMusicTech Poland is an initiative emerging in response to the rapidly blurring boundaries between the music sector and the new technology industry. The primary goal of MusicTech Poland is to build a community integrating those interested in the development and exploration of the MusicTech sector. We bring together musicians, developers, entrepreneurs, and innovators to shape the future of music technology in Poland. MusicProject
  10. MemoSonic: Building an Audio Memory GameThe story behind MemoSonic, a Flutter-based educational game that turns sound recognition into play, with accessibility for visually impaired users. MusicArticle

2023

6 entries

  1. Vimo SwimProgrammable swim metronome that sits under the swim cap, plus free apps for swimmers and coaches. Formerly BeatBuddy. I founded it and lead the engineering. Now in a testing program with Total Immersion coaches in Poland and Spain. SportProject
  2. Dev Meeting 004: Introduction to Event StormingMy notes on Event Storming, a workshop-style method for exploring complex systems and business domains by mapping the flow of events and interactions. AI & codeArticle
  3. Dev Meeting 003: Web3 PrimerMy notes from a Web3 primer. Learn how network interactions are evolving and why companies are adopting Web3 elements in their projects. AI & codeArticle
  4. MusicTech LabSoftware company for the music industry that I founded in 2023. The team builds tools such as royalty analytics and AI content platforms, and publishes open source music metadata tools. MusicProject
  5. Dev Meeting 002: Intro to DDDMy notes from an introduction to Domain-Driven Design (DDD), an approach to software development that models business domains for more effective and maintainable systems. AI & codeArticle
  6. Dev Meeting 001: Kubernetes is a FrameworkMy notes on Kubernetes as a framework: from Google's scaling challenges and Borg to Operators, CRDs, and modern container orchestration basics. AI & codeArticle

2022

3 entries

  1. 2015 to 2022 · Past life

    Product agency

    Founder and CEO of Bravelab

    A software company that built web platforms and MVPs for clients in travel, education, e-commerce and media. Many of them were non-tech founders with a big idea and a small budget.

    What I took with me How to turn an idea into a plan and a budget a founder can check, and how to run a team that people want to stay in.

    PythonDjangoVue.jsPostgreSQLReact Native
    Profit sharing at Bravelab 4DX at Bravelab
  2. Did You Know? 10 Developer Tips from Real CodebasesA collection of practical software development tips, workarounds, and clever solutions discovered in production codebases. Part 1 of an ongoing series. AI & codeArticle
  3. Total Immersion CracowFreestyle swimming courses in Kraków using the Total Immersion method. I coach there, and it is where my sport products meet real swimmers first. SportProject

2021

6 entries

  1. EF SET Certificate (C1 Advanced)EF Standard English Test OtherCertificate
  2. Closer MusicMusic streaming and discovery platform designed to connect artists with fans. A web application focused on building closer relationships between musicians and their audience through personalized content and direct engagement features. MusicProject
  3. Holacracy why and where we areI have been testing Holacracy with my team at Bravelab.io for 6 months. Companies are complex organisms. We gave ourselves the space to experiment. OtherArticle
  4. The very first attempt to implement 4DX in Bravelab.ioA real-life example of implementing the Four Disciplines of Execution framework in a software development company. Learn what worked, what didn't, and how to get started with 4DX. OtherArticle
  5. A quick introduction to profit sharing implementationMy company does not offer any employee benefits. Learn how we implemented a simple profit sharing system and whether it's worth considering for your organization. OtherArticle
  6. WundrTravel discovery platform that helps users find unique experiences and hidden gems. MVP built for non-tech founders, featuring curated recommendations, personalized itineraries, and a community-driven approach to travel exploration. OtherProject

2020

1 entry

  1. Design Thinking In PracticeWe are very OtherCertificate

2019

3 entries

  1. Postgraduate Studies in IT Business ManagementAGH University of Kraków OtherCertificate
  2. Happy Relations: Tuckman's stages and CliftonStrengths in team buildingAgile Nuts OtherCertificate
  3. Team Kanban PractitionerLean Kanban University OtherCertificate

2018

4 entries

  1. Only a few books but dozens of ideasKey takeaways from Bill Gates' recommended book list, including Getting Things Done, Deep Work, and practical ideas for time management and productivity. OtherArticle
  2. Memosonic AppMobile application that combines music with memory and learning. An innovative approach to audio-based education and recall, using sound patterns to enhance memory retention and create engaging learning experiences. MusicProject
  3. Management 3.0 FoundationManagement 3.0 OtherCertificate
  4. Gcloud pubsub exampleExample of event-driven audio analysis on Google Cloud Run with Pub/Sub. Open source Python code on my GitHub. AI & codeProject

2016

1 entry

  1. Arduino and midi AbletonArduino MIDI controller with two buttons for Ableton Live. Open source C++ code on my GitHub. MusicProject

2015

1 entry

  1. 2010 to 2015 · Past life

    Custom software

    Founder of Sizeof

    My first company. Custom IT projects for many clients: admin panels, loyalty systems and online shops.

    What I took with me How to sell, estimate and deliver on my own, and keep clients for years.

    PythonDjangoPostgreSQLLinuxJavaScript

2010

1 entry

  1. 2006 to 2010 · Past life

    Loyalty and marketing tech

    Full stack engineer, then team leader at hyperCREW

    Loyalty programmes and online campaigns for big brands, built in Wrocław.

    What I took with me How to ship for big brands on fixed launch dates, when the campaign starts whether the code is ready or not.

    PHPMySQLJavaScriptAJAX

Kind words

8 entries

  1. Michael FiorentinoMichael FiorentinoI 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. OtherTestimonial
  2. Clarence SittampalamClarence SittampalamMariusz 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. OtherTestimonial
  3. Matt BristowMatt BristowMarius 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. OtherTestimonial
  4. Imran AzizImran AzizMariusz 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. OtherTestimonial
  5. Jack CloughJack CloughWorking 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. OtherTestimonial
  6. Scott CloverScott CloverI 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 OtherTestimonial
  7. Roberto CruzRoberto CruzAs 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. OtherTestimonial
  8. Aiden CampbellIt 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. OtherTestimonial

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