Marvin Heyne
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Projects

2023 to 2026

14 projects, each with its own page.

Built outside paid work. Startup work lives under Experience.

  1. project files14projects, 2023 to 2026
  2. GitHub links10with a public repository
  3. field “kind”3of them built at hackathons
  4. “X of Y commits”373own commits, where counted

Project index

filter by field

14 of 14 shown

Project index
Year Project Kind Field Evidence Code
2025 PneuNet Pneumonia detection on chest X-rays, from a NumPy CNN to a DICOM viewer. Research Machine learning >87% classification · >95% segmentation GitHub ↗
2026 ESN Event Hub Process analysis and a small web app for Erasmus Student Network Potsdam. Course project Web Team of five · grade 1.3 pending
2026 MediaSync Android backups to a USB stick, no cloud. App Mobile Solo · about 26k lines of Kotlin pending
2025 Bundesliga fan app Fan app with AI chat on AWS; winning team. Hackathon Mobile, Agentic AI Repo owner · 18 of 89 commits GitHub ↗
2026 GorillaScout Bachelor's project on re-identifying wild gorillas from camera-trap video. Bachelor's project Machine learning Ongoing · team of eight GitHub ↗
2026 Agentic product with BMW An agentic system that spots early warning signs of unplanned machine stops. Course project Agentic AI Ongoing · team of six · under NDA pending
2026 Voya Agent that matches founders with co-founders and investors, with a voice role-play. Hackathon Agentic AI, Web Technical lead · 130 of 142 commits GitHub ↗
2026 takeøff website Bilingual site for a student cultural collective, Canvas scenes, no tracking. Website Web 32 of 33 commits in five days GitHub ↗
2026 Sicily trip planner Planning tool a group of five actually used for a trip. Tool Web Solo · 51 commits GitHub ↗
2026 Thesinator AI-guided thesis journey: matching, future simulation, voice. Hackathon Agentic AI, Web +10,546 lines in 5 of 27 commits GitHub ↗
2026 PowerSqueak Brownfield work on a seven-year-old Smalltalk presentation tool. Course project Software engineering 38 commits · ~4,800 lines · grade 1.0 GitHub ↗
2026 ¡Vamos! Offline Spanish app with spaced repetition and a browser-side AI tutor. Tool Web Solo · 34 commits in two days GitHub ↗
2025 OweFlow Flutter app for splitting group expenses; I owned auth. App Mobile 43 of 120 commits GitHub ↗
2026 TouchdownTactics Real-time strategy game in Squeak/Smalltalk; I owned the cards and the elixir. Course project Software engineering 38 commits · team of seven · grade 1.0 pending

Specimen sheets

preview, role, evidence, code
Four students and a juror with certificates at the Jugend forscht national final
Jugend forscht national final, Heilbronn 2024
The team at the AI Pneumonia Detection stand with posters and a screen
PneuNet at the Thuringian state round, Jena 2024
From a NumPy CNN to the DICOM viewer
DICOM viewer with a chest X-ray and the detected pneumonia region outlined in red
Detection in the DICOM viewer
DICOM viewer showing only the segmented lungs of a chest X-ray
Lung segmentation
Two chest X-rays overlaid with class activation heatmaps
Class activation maps: where the network looks
Qt viewer with four chest X-rays, one with a marked finding
Qt/C++ viewer, four images side by side

Specimen 01Jugend forscht state winner

PneuNet

Pneumonia detection on chest X-rays, from a NumPy CNN to a DICOM viewer.

Project post with live demo →

Period
2023 – 2025
Role
Sole author of the code; team of three at Jugend forscht
Kind
Research · Machine learning
Evidence
>87% classification · >95% segmentation
Stack
Python, NumPy, PyTorch, TensorFlow, OpenCV, Qt, C++
  • A CNN written from scratch in NumPy, including backpropagation.
  • Seven CNN architectures compared in PyTorch on four public datasets of up to 30k images, then lung segmentation and class activation maps in a Qt/C++ DICOM viewer.
  • Jugend forscht 2024: Thuringian state winner and a special prize at the national final. All 60 commits are mine.

Started as a high-school research project and continued at Jugend forscht. Results are from the project's own validation split, not a clinical validation.

Specimen 02

ESN Event Hub

Process analysis and a small web app for Erasmus Student Network Potsdam.

Project post with live demo →

Period
Summer term 2026
Role
Interviews, process analysis and presentations in a team of five
Kind
Course project · Web
Evidence
Team of five · grade 1.3
Stack
BPMN, Next.js, Google Sheets API, Vercel
Links
Release pending
  • Stakeholder interviews and a BPMN model of the as-is process; 15 pain points prioritised; the concept makes the event the single source of truth, with a view for each role.
  • The team shipped a Next.js app on Vercel with a Google Sheet as data store, so it costs nothing to run: organiser board, sign-up without login with a waitlist, and an event log that checks real events against the designed process.
  • My part: one of the stakeholder interviews, the closing part of the interim presentation and the opening slides of the final one. Module grade 1.3.

Course project in Foundations of Enterprise Applications at HPI with ESN Potsdam, a volunteer organisation that runs about 80 events per semester across six tools. We interviewed people in different roles, modelled the process in BPMN and shipped a prototype as a team. The code lives in a teammate's private repository; the preview is an illustration with sample data.

Specimen 03

MediaSync

Android backups to a USB stick, no cloud.

Project post with live demo →

Period
Apr – Sep 2026
Role
Solo
Kind
App · Mobile
Evidence
Solo · about 26k lines of Kotlin
Stack
Kotlin, Jetpack Compose, Hilt, Room, WorkManager, USB Host API
Links
Release pending
  • Incremental backups with hash-based deduplication and chunked copying; restore included.
  • Foreground service with notifications, reminder worker, Quick Settings tile, three home-screen widgets and a share target.
  • Repository is being prepared for release on GitHub, so there is no link yet.

An Android app for incremental photo and video backups to USB storage and back. About 26k lines of Kotlin in 155 files. The repository is being prepared for release on GitHub.

Bundesliga fan app, AI chat tab: Bundesliga logo, five FAQ buttons and an input with voice button
Illustration, not a screenshot: Bundesliga fan app chat: a fan asks how to buy tickets, the assistant answers (sample answer, backend offline)

Specimen 04Winning team

Bundesliga fan app

Fan app with AI chat on AWS; winning team.

Project post with live demo →

Period
Mar 2025 · main build in three days
Role
Repository owner in a team of three
Kind
Hackathon · Mobile, Agentic AI
Evidence
Repo owner · 18 of 89 commits
Stack
Expo, React Native, TypeScript, AWS API Gateway
  • Tabs for matches, videos, table and statistics, plus an AI chat against an AWS API Gateway backend.
  • Quiz mode with text-to-speech; my part included the project setup, the chat UI and native sharing with fallbacks.
  • One of six winning teams at the Bundesliga Hackathon 2025.

Cross-platform app (Expo, React Native; web, iOS, Android) built for the first Bundesliga Hackathon 2025 by DFL, AWS and EintrachtTech. The screens come from the final prototype, run locally. The AWS backend is switched off, so the chat answer shown is a sample.

Specimen 05

GorillaScout

Bachelor's project on re-identifying wild gorillas from camera-trap video.

Project post with live demo →

Period
Since Oct 2026
Role
One of eight students (ongoing)
Kind
Bachelor's project · Machine learning
Evidence
Ongoing · team of eight
Stack
  • The pipeline goes from detection to tracking to re-identifying individual animals and counting the population. Previous cohorts built it; our cohort continues it.
  • To get started I worked through the previous cohorts' theses and the group's WACV 2026 paper and, with AI assistance, turned them into a sourced study guide.
  • The demo rebuilds the project's web platform, which earlier cohorts built (not my work), with invented sample data and drawn stand-in videos, not real camera-trap footage or model output.

HPI bachelor's project at Prof. Gerard de Melo's AI chair. It continues a multi-year pipeline that detects, tracks and re-identifies wild gorillas in camera-trap video. The project started in October 2026 and runs until summer 2027; there are no results of mine yet.

Specimen 06

Agentic product with BMW

An agentic system that spots early warning signs of unplanned machine stops.

Project post with live demo →

Period
Since Sep 2026
Role
Team of six (ongoing)
Kind
Course project · Agentic AI
Evidence
Ongoing · team of six · under NDA
Stack
Python, pandas, DuckDB, Parquet, pytest, LLM agent with tools
Links
Release pending
  • Problem: in highly automated production, machines report errors all the time, and the early signs of an unplanned stop are easy to miss.
  • Approach: deterministic code computes every number; an LLM agent only investigates through tools, explains what it finds and routes it to the right people; a human approves anything written back to the ERP system.
  • I took part in the on-site user interviews with the partner and built the reporting and early-warning pipeline.

Seminar Trends and Concepts – Building Agentic Products at HPI, with BMW as industry partner. The details are confidential, so this entry only covers the problem, the approach and the technologies. The final presentation is in January 2027.

Voya on a phone: the profile scout asks whom you want to meet, with a button to start a voice conversation

Specimen 07Participation

Voya

Agent that matches founders with co-founders and investors, with a voice role-play.

Project post with live demo →

Period
Sep 2026 · 48 hours
Role
Technical lead in a team of three to four
Kind
Hackathon · Agentic AI, Web
Evidence
Technical lead · 130 of 142 commits
Stack
Next.js 16, TypeScript, OpenAI Agents SDK, OpenAI Realtime API, Cloudflare Workers
  • Ranks 569 real conference profiles with an explainable, deterministic match score.
  • Split the work into 30+ ownership packages; parallel AI coding agents ran in 50+ git worktrees.
  • Rule-based fallbacks keep the demo running without an API key. No prize; the MVP runs on Cloudflare Workers.

Built at the OpenAI Hackathon at IdeaLab! 2026 (WHU Vallendar). An agent interviews a founder by text or voice, derives a search profile, ranks real conference profiles, drafts personality-adapted outreach and offers a voice role-play to prepare the conversation.

Start page of the takeøff website: logo over a night-sky Canvas scene and the next event

Specimen 08

takeøff website

Bilingual site for a student cultural collective, Canvas scenes, no tracking.

Read the project post →

Period
Sep 2026 · five days
Role
32 of 33 commits
Kind
Website · Web
Evidence
32 of 33 commits in five days
Stack
Next.js 16, TypeScript, Vanilla CSS, Canvas 2D, Vercel
  • Adapter-based data gateway (JSON today, a database later) and contract-driven data types that generate the editing forms.
  • Dependency-free Canvas scene engine: three themes in day and night versions, three effect levels, reduced motion respected.
  • Automated UI and performance audits across eight viewport widths.

Bilingual site for takeøff, a student cultural collective in Potsdam. Live on Vercel; some content is still placeholder.

Specimen 09

Sicily trip planner

Planning tool a group of five actually used for a trip.

Project post with live demo →

Period
Mar – Apr 2026
Role
Solo
Kind
Tool · Web
Evidence
Solo · 51 commits
Stack
JavaScript, GitHub Pages, Cloudflare Workers, GitHub API
  • Pages for accommodation, flights, car, activities, packing list, budget, votes, idea wall, day plan and tasks.
  • Cloudflare Worker for GitHub OAuth, data sync through the GitHub API and a scraper that reads offer links.
  • The group of five planned their trip with it.

A static multi-page site on GitHub Pages with a Cloudflare Worker behind it.

Thesinator stakeholder map: a live graph linking the student to topics, companies and the university Thesinator thesis list: best-matching thesis topics with the reason why each fits Thesinator "ask your future self": a chat with a simulated future career for one thesis path Thesinator simulation progress: stakeholder map, future path and thesis matches being built

Specimen 10Participation

Thesinator

AI-guided thesis journey: matching, future simulation, voice.

Project post with live demo →

Period
Mar 2026
Role
Chat, networking and browse features
Kind
Hackathon · Agentic AI, Web
Evidence
+10,546 lines in 5 of 27 commits
Stack
React, TypeScript, Supabase, pgvector, Edge Functions, Python
  • Embedding-based topic matching on Supabase with pgvector, a multi-agent simulation of your future stakeholders and a voice interface.
  • My part: chat, networking and browse features with 20+ React components, two Supabase Edge Functions, migrations and session persistence.
  • START Hack 2026, St. Gallen: participation, no prize.

Built at START Hack 2026 in St. Gallen for the Studyond challenge. Participation, no prize.

Specimen 11

PowerSqueak

Brownfield work on a seven-year-old Smalltalk presentation tool.

Project post with live demo →

Period
Apr – Jul 2026
Role
Feature owner for sections and timer in a team of seven
Kind
Course project · Software engineering
Evidence
38 commits · ~4,800 lines · grade 1.0
Stack
Squeak/Smalltalk, Morphic, SUnit, GitHub Actions, smalltalkCI
  • Named, nested slide sections: model, headers in the thumbnail sidebar, collapse state that persists, indent and outdent with Tab, n and p to jump while presenting, save and load.
  • An LED presentation timer built as a small subclass of the existing timer morph. I also traced a keyboard-focus bug into the UI framework's event routing and fixed it with a regression test.
  • Set up CI with GitHub Actions and smalltalkCI, made the tool run on Squeak 6.1 and rewrote the README. Module grade 1.0.

Software Engineering I at HPI: our team of seven took over the open-source presentation tool PowerSqueak and extended it over nine sprints with weekly customer meetings and pair programming. Team test coverage went from 84% to 95%.

¡Vamos! home screen with the daily goal and twelve practice modes

Specimen 12

¡Vamos!

Offline Spanish app with spaced repetition and a browser-side AI tutor.

Read the project post →

Period
Aug 2026 · two days
Role
Solo
Kind
Tool · Web
Evidence
Solo · 34 commits in two days
Stack
JavaScript, PWA, Service Worker, localStorage, GitHub Pages
  • Spaced repetition, multiple choice, accent-tolerant typing, text-to-speech and verb tables for seven tenses.
  • Optional AI tutor that runs with your own key, entirely in the browser; Anki export.
  • Content lives in 74 JSON files registered through manifests: a new chapter is a new file.

A vanilla-JavaScript PWA for learning Spanish up to B1/B2, offline and without an account. Live on GitHub Pages.

Specimen 13

OweFlow

Flutter app for splitting group expenses; I owned auth.

Project post with live demo →

Period
Dec 2024 – Jan 2025
Role
43 of 120 commits
Kind
App · Mobile
Evidence
43 of 120 commits
Stack
Flutter, Dart, Firebase Auth
  • Groups, debt tracking, reminders and analytics.
  • I owned authentication: email verification and social login on Firebase.
  • Stopped when payment regulation made the transfer feature impractical for two students.

A Flutter prototype built with a fellow student. There is no public build, so the demo is rebuilt from the source code and runs on sample data.

Specimen 14

TouchdownTactics

Real-time strategy game in Squeak/Smalltalk; I owned the cards and the elixir.

Project post with live demo →

Period
Nov 2025 – Jan 2026
Role
Card, hand and elixir subsystem in a team of seven
Kind
Course project · Software engineering
Evidence
38 commits · team of seven · grade 1.0
Stack
Squeak/Smalltalk, Morphic, SUnit, Squot/git
Links
Release pending
  • Players spend elixir to play heroes and spells from a hand of cards; units find their path and fight. Bot opponent with four difficulty levels, wave mode, tutorial and local multiplayer.
  • My part was the hand, card and elixir subsystem: deck cycle, selection and play logic, elixir regeneration and spending, and the UI morphs, refactored over several iterations.
  • The team code uses Abstract Factory, Strategy, Template Method, Null Object and Flyweight. Module grade 1.0.

Built in the Software Architecture course at HPI as a team of seven: a card-based tower-rush game in Squeak/Smalltalk, with design patterns applied throughout. The repository belongs to the course and is private, so the preview is a rebuilt illustration.