Marvin Heyne
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looking back, newest first

Notes, written shortly after the event.

Looking back at competitions, hackathons, trips and work, each written down a few days later. Every post says when it was written and what it is about.

  1. post files35posts
  2. field “written”3years
  3. words / 20093minutes of reading, total
  4. tags74topics
35 of 35 shown

202628

  1. Deep learning without the exam: why I rebuilt the course book as a website

    This term I'm sitting in on the Deep Learning lecture at HPI. To really understand the material, I rewrote the first part of the course book as a simplified German study site with interactive demos.

    Interim update, written during the term.2 min read

    • machine-learning
    • web
    • learning
    • university

  2. An agentic system with BMW: the code calculates, the model explains

    In the seminar Building Agentic Products we're working with BMW on a system that spots early warning signs of unplanned machine stops. An interim update, as abstract as confidentiality requires.

    Interim update, written shortly after the first interim review.3 min readLive demo

    • ai-agents
    • industry
    • python
    • university

  3. GorillaScout: getting into a pipeline that four cohorts built before us

    Since October I've been in the bachelor's project that re-identifies wild gorillas in camera-trap video. An interim update on how you get into a pipeline that four cohorts built before you.

    Interim update, written in the project's first month.3 min readLive demo

    • machine-learning
    • computer-vision
    • bachelors-project
    • university

  4. Kobe: what I actually built as founding engineer

    The Launchpad series tells the three weeks from the inside. This post explains the product: an agent that finds the best path to a person through your own network, and my part in it.

    Looking back, written a few days after my last Kobe commit.4 min readLive demo

    • kobe
    • ai-agents
    • cloudflare
    • startup

  5. Launchpad, part 5: Demo day

    A pitch to investors, the result as announced to the teams, and two weeks in Pennsylvania as date lines.

    Looking back, written the day after demo day. Part 5 of 5 of the Launchpad series.3 min read

    • launchpad
    • kobe
    • startup
    • pitch
    • usa

  6. Launchpad, part 4: Revenue, not points

    Week two: an elimination that turned into a revenue ranking, a pitch round down to five teams, and people giving away their day off.

    Looking back, written the evening before demo day. Part 4 of 5 of the Launchpad series.3 min read

    • launchpad
    • kobe
    • startup
    • pitch

  7. Launchpad, part 3: Ten interviews, completely useless

    Through the first elimination, users who look past the bugs, and the sentence that took my engineering reflex apart.

    Looking back, written at the end of our first week at camp. Part 3 of 5 of the Launchpad series.3 min read

    • launchpad
    • kobe
    • startup
    • sales

  8. Launchpad, part 2: "Your system has run out of application memory"

    New York, a bus from Times Square, a camp in the woods and two nights in which first the laptops and then we hit our limits.

    Looking back, written on the morning of the first elimination day. Part 2 of 5 of the Launchpad series.3 min read

    • launchpad
    • kobe
    • startup
    • usa

  9. Launchpad, part 1: Seven days before

    A call from René, twenty minutes to decide, Tenerife cancelled and one week of building before the flight to New York.

    Looking back, written on the day we flew to New York. Part 1 of 5 of the Launchpad series.3 min read

    • launchpad
    • kobe
    • startup
    • usa

  10. Voya: 48 hours, more than 50 worktrees, no prize

    At the OpenAI hackathon at IdeaLab! in Vallendar I coordinated parallel AI coding agents. We didn't win, but the MVP is live.

    Looking back, written the day after the hackathon.2 min readLive demo

    • hackathon
    • openai
    • ai-agents
    • nextjs

  11. MediaSync: photos from your phone to a USB stick, no cloud

    For half a year I built an Android app on the side that backs up photos and videos straight to a USB stick. About 26,000 lines of Kotlin, on my own.

    Looking back, dated to the day of the last commit.3 min readLive demo

    • android
    • kotlin
    • app
    • backup

  12. A website for takeøff in five days, with a night sky and no tracking

    Our cultural collective in Potsdam needed a website. I built it in five days, bilingual, with my own Canvas scene engine and a data layer that can take a database later.

    Looking back, dated two days after the last commit.3 min read

    • web
    • nextjs
    • canvas
    • takeoff
    • volunteering

  13. Eight months at MitJulia: what you learn when an AI answers the phone for hair salons

    Since January I've been working on Julia, the AI receptionist by MitJulia (formerly Friseurtelefon). A progress report with numbers.

    Looking back, written after closing the timeout and alerting tickets in early September.3 min readLive demo

    • mitjulia
    • voice-agent
    • aws
    • testing

  14. Organising startup tours: Munich, Amsterdam and zero replies

    Since February I've been organising startup tours at HPI Engine. What worked in Munich and what Amsterdam taught me about cold outreach.

    Looking back, written after the feedback meeting on both tours.3 min read

    • hpi-engine
    • startups
    • organising

  15. ¡Vamos!: a Spanish app in two days, offline and without an account

    My school Spanish is B1 and getting rusty. So I built myself a small learning app that runs in the browser, works offline and doesn't ask you to sign up.

    Looking back, dated two days after the last commit.3 min read

    • web
    • pwa
    • javascript
    • languages

  16. Project Midas: a fund that looks too good, and three mistakes inside it

    For a seminar on statistical fallacies I built a synthetic trading dataset with three hidden biases. Plus a talk on hallucination in language models.

    Looking back, dated to the end of the summer term. The grade is added as a note at the end.3 min read

    • data
    • statistics
    • machine-learning
    • llm
    • university

  17. PowerSqueak: seven-year-old code, nine sprints and a bug in the event routing

    In the Software Engineering course we took over an old presentation tool written in Smalltalk and kept building it. My features: slide sections and a presentation timer.

    Looking back, dated three days after the code defense. The grade is added as a note at the end.3 min readLive demo

    • smalltalk
    • software-engineering
    • legacy-code
    • testing
    • university

  18. ESN Event Hub: six tools, one event and why we built it boring

    For the Erasmus Student Network in Potsdam we mapped the event process, modelled it and shipped a small web app as a team. Understand first, then build.

    Looking back, dated three days after the final presentation. The grade is added as a note at the end.3 min readLive demo

    • processes
    • bpmn
    • nextjs
    • interviews
    • university

  19. A school day for 87 eleventh-graders, and how it got there

    As an sdw scholar I led the school outreach for our regional group's social day. On July 1 it happened.

    Looking back, written two days after the school day.2 min read

    • sdw
    • volunteering
    • scholarship
    • potsdam

  20. AWS World Sports Innovation Cup: research first, then build, then Frankfurt

    We won the AWS World Sports Innovation Cup 2026 with the Connected Arena challenge, and I pitched in the final.

    Looking back, written a few days after the final at the DFB campus.2 min read

    • hackathon
    • aws
    • sport
    • design-thinking

  21. Five people, one trip to Sicily and a planning tool in twelve days

    Instead of a spreadsheet and three group chats I built our travel group a small planning site with votes, a budget and a day plan.

    Looking back, dated two days after the last commit.2 min readLive demo

    • web
    • javascript
    • cloudflare
    • travel

  22. START Hack in St. Gallen: no prize, a good prototype

    Straight from the road trip to START Hack: 36 hours on an AI-guided thesis journey for Studyond.

    Looking back, written the day after the trip home from St. Gallen.2 min readLive demo

    • hackathon
    • ignite
    • supabase
    • ai-agents

  23. Arctic Sprint, part 3: Lovable, Soundboks and back in Berlin at 4 am

    Two office visits, one product decision, and 17 days that end with cleaning a van.

    Looking back, written the day after we got home.2 min read

    • arctic-sprint
    • kobe
    • travel-and-code
    • local-first

  24. Arctic Sprint, part 2: Arctic Circle, northern lights, Lofoten in a storm

    Why we skipped the North Cape and what we got instead.

    Looking back, written on the way south from the Lofoten islands.2 min read

    • arctic-sprint
    • kobe
    • travel-and-code

  25. Arctic Sprint, part 1: by van from Berlin to Helsinki

    Exams done, a van from the startup, a laptop on the passenger seat: week one of our travel-and-code road trip.

    Looking back, written on the way north out of Helsinki.2 min read

    • arctic-sprint
    • kobe
    • travel-and-code

  26. Red Cross medic in civil protection, next to a full semester

    I've volunteered with the German Red Cross in Potsdam since October 2024. This winter it was a major fire and black ice.

    Looking back, written in late February 2026 after the black ice deployment.2 min read

    • red-cross
    • volunteering
    • potsdam

  27. 800 runs of dig: what one semester of internet measurement taught me

    In the English-language course Introduction to Internet Measurements I designed, ran and analysed a measurement every week. The last one was my own RIPE Atlas study.

    Looking back, dated to the end of the term, just before the road trip.3 min readLive demo

    • data
    • networking
    • python
    • dns
    • university

  28. TouchdownTactics: seven people, one game in Smalltalk, and I had the cards

    In the Software Architecture course a team of seven built a real-time strategy game in Squeak/Smalltalk. My part: hand, cards and elixir.

    Looking back, dated two days after the hand-in. The grade is added as a note at the end.3 min readLive demo

    • smalltalk
    • software-architecture
    • design-patterns
    • university

20253

  1. ReThink Recycling: live trash detection without a GPU

    At the Siemens × AWS hackathon in Berlin I built real-time trash detection, and our team took first place.

    Looking back, written a few days after the hackathon.2 min read

    • hackathon
    • computer-vision
    • sustainability

  2. Bundesliga Hackathon: three days, 71 commits, one of the winning teams

    Building a chatbot app for the Bundesliga with Hasso's Kickers at the first Bundesliga Hackathon by DFL, AWS and EintrachtTech.

    Looking back, written a few days after the final in Frankfurt.3 min readLive demo

    • hackathon
    • react-native
    • aws

  3. OweFlow: 120 commits, then the question about money

    A fellow student and I spent a month building a Flutter app that splits group expenses. What stopped us wasn't the code but payment regulation.

    Looking back, dated a few days after the last commit.3 min readLive demo

    • flutter
    • firebase
    • app
    • startup-idea

20244

  1. Ratard: from a one-minute pitch to a browser extension in a week

    We won Best Pitch at HPI Engine's E-Challenge with an idea against fake news. A week later I started building it.

    Looking back, dated to the end of the prototype week.3 min read

    • prototype
    • browser-extension
    • fake-news
    • hpi-engine

  2. First week at HPI: why I picked the small one

    80 places a year, a selection process with an aptitude test, and a decision against some big names.

    Looking back, written in my first week of lectures.2 min read

    • hpi
    • university
    • potsdam

  3. Karate since childhood and a national championship before my school certificate

    Seventh place at the German championships in my hometown, six days before my Abitur certificate.

    Looking back, written the day after the German championships in Erfurt.2 min read

    • karate
    • sport
    • erfurt

  4. PneuNet: eighteen months of chest X-rays, three competition rounds

    How a school research project on pneumonia detection made it to the national final of Jugend forscht, and why the DICOM viewer is the real product in the end.

    Looking back, written a few days after the national final in Heilbronn.3 min readLive demo

    • jugend-forscht
    • machine-learning
    • school