Janne Keipert

A local-first record collection tracker for vinyl, CDs, cassettes and digital copies. Catalogue what you own, including condition, price paid, and where and when you bought it, through a scan-first add flow backed by Discogs, with MusicBrainz as a fallback. Every release gets a detail view whose colours are derived from the sleeve and a format mark that leans the record, disc or shell out from behind the cover. A wishlist tracks what you are still hunting, Roll picks something off the shelf when you cannot decide, and a friends feed shows what the people you follow added or are looking for. The app works fully without an account and keeps everything on the device; signing in adds field-level last-write-wins sync across devices, sleeve photos and a shareable public shelf. Expo app for the phone, available on the App Store, plus a React web app for the desktop library.

A self-hosted game server management platform that makes it simple and beautiful to deploy, manage, and monitor game servers on your own hardware. Cosy provides a modern web UI for full container lifecycle management, real-time metrics and logs, file browsing, user and quota management, RCON integration, and event-driven webhooks. Servers are created from a curated template library and run as Docker containers, with support for both Docker Compose and Kubernetes deployments. We also created a dedicated Minecraft Fabric mod which collects in-game metrics like TPS and player count and pushes them back to the platform.

A subdomain management service for the cosy-hosting.net platform. Users register an account, claim subdomains (e.g. castle.play.cosy-hosting.net), and point them at their own Cosy instance IP, and the backend automatically provisions and updates the corresponding AWS Route53 A records. A Cosy+ billing tier (via Stripe) unlocks custom label choice, CNAME support, and higher quotas. The backend is a Spring Boot 4 / Java 21 REST API with JWT auth, rate limiting, and a Prometheus metrics endpoint. The frontend is a React 19 SPA with full i18n (EN/DE), TOTP two-factor authentication, Cloudflare Turnstile bot protection, and QR code setup for 2FA. Both services are containerized, deployed to Kubernetes via Kustomize and ArgoCD, and covered by a Playwright end-to-end test suite.

A local-first, keyboard-driven SSH client for the terminal. Hosts, keys and sessions live in an encrypted local vault and work entirely without an account; signing in only adds the online features, namely cross-machine sync and shared team projects, under a zero-knowledge model in which the server never sees anything but ciphertext. The flagship client is a Go and Bubble Tea TUI with real SSH support (agent, key file, password and keyboard-interactive auth), detachable tabbed sessions with scrollback replay, port forwarding, host tagging and three themes. It is complemented by a web app that serves the landing page and the browser-based authentication flow, a Spring Boot sync backend, and a React Native companion app for iOS and Android. The master password is stretched into the vault key with argon2id on the client, vault blobs are sealed with XChaCha20-Poly1305 before upload, terminal sign-in happens through a browser device-code pairing so no password is ever typed into the terminal, and the only recovery path is a 40-character recovery code shown once during onboarding. Team projects share hosts through a per-project key that is distributed to members as sealed boxes; private keys are never shared.

A mobile app (React Native/Expo) for discovering and tracking Die drei ??? audiobook albums. It randomly suggests an unseen album from the full catalog, lets you open it directly on Spotify, Apple Music, or Deezer, and tracks your listening history. A history screen shows your overall progress across the entire series with filtering by narrator, album type, and other criteria. Album details include descriptions, narrator characters, ratings, and release dates. Push notifications alert you when new albums are released.

A full-stack web application for administering and tracking athlete performances for the Deutsche Sportabzeichen (German Sports Badge). Trainers can register athletes, record performances across disciplines like endurance, strength, speed, and coordination, and track medal eligibility based on age- and gender-specific thresholds. Athletes can view their own progress, certificate status, and medal history. The platform features role-based access control, real-time updates via WebSocket, and multi-language support.

A full-stack web app that connects to a user's Steam library and displays their games with high-quality custom cover artwork from SteamGridDB. Users enter their Steam profile URL to load their game collection, including Family Shared titles, and can browse alternate, static, and animated cover styles for each game. The backend reactively fetches and caches cover metadata, while the frontend provides a responsive browsing experience with smooth animations.

A community-driven web platform for discovering, creating, and sharing ability lineups for the tactical shooter Valorant. Players can browse lineups filtered by map, agent, and ability, visualized on interactive canvas-based maps showing stand and landing positions. Authenticated users can create their own lineups with screenshot uploads, organize them into guides, and share them with the community.

A distributed event-driven message publishing and subscription platform. Users create projects with topics that other projects can subscribe to. When a message is published to a topic, it is automatically delivered to all approved subscribers via HTTP webhooks with retry logic and exponential backoff. The system features multi-tenant project isolation, fine-grained role-based access control, and full HTTP exchange logging for debugging delivery issues.

A price-tracking and notification service for Star Citizen ships. The app monitors the Roberts Space Industries pledge store for pricing changes and sends email notifications when ships within a user's configured price range go on sale or get discounted. Users can register, set minimum and maximum price thresholds, and receive hourly updates via email.

A cloud-native student management portal built as a microservices and micro-frontend architecture in a university agile software engineering course. Multiple teams each develop independent domain services (room booking, timetable management, document management, examination grading, notifications, parking analytics, and more), all composed into a unified single-spa frontend. The system uses Keycloak for centralized authentication, MinIO for file storage, and is fully containerized for Kubernetes deployment.

The school finals project of my computer science course. A 2D side-scrolling action platformer Metroidvania game built in our own 2D Game Engine completely from scratch using JavaX Swing. The player traverses a tile-based world with physics-driven movement including running, jumping, wall-jumping, and dashing. Enemies, liquids, coins, fireballs, and interactive event areas populate the world, which is loaded from JSON map data. The game features a skill tree with upgrades, a minimap, HUD with health display, sprite animations, a camera system, and background music. A companion website built with Vue.js serves as a landing page and tutorial hub.

A mail service which allows the users to configure SMTP connections and then use an API to send mails through those connections. Mails are being kept in storage for 30 days for monitoring and then deleted from storage.

A multi-tenant, in-cluster Kubernetes database browser. Strata runs inside a Kubernetes cluster, automatically discovers the databases running in that cluster, and lets authenticated users browse and query the ones they've been granted access to, without kubeconfig files, manual connection strings, or port-forwarding. It supports PostgreSQL, MySQL, MongoDB, Redis, InfluxDB, and Loki. Features include role-based access control with namespace- and database-level grants, a global safe-mode for production namespaces, audit logging, user management, drag-and-drop grouping of datasources, and a full GitOps deployment model via ArgoCD.