deen
deen

[ Software | UX ] Developer

I am a full-stack developer from Saarland and build web applications from the database schema to the interface, along with the infrastructure they run on.

Write to meView CV

What interests me is the whole system: the interface, the server behind it and sometimes the firmware on the device as well.

My name is Matthias Gießelmann, I come from Saarland and have worked as a developer since 2012. I started out with websites; today I develop complete web platforms, including frontend, backend and infrastructure.

When I lack a tool for a task, I write it myself. That is how plxr, a terminal for working with several coding agents at once, and an editor for ESP32 displays came about. Before I start building, I write down in a specification what the software is meant to do. That saves a lot of time later on.

In my spare time I like to cook and barbecue, work with wood in the workshop or travel with the camping box in the boot. At home I run a small homelab, and in the evenings The X-Files or Star Trek are often on.

Place of birth
Ottweiler
Date of birth
3 April 1988
Residence
Homburg Saar
Degree
Bachelor of Science

  • Software for everyday use

    I develop applications that people use every day. For me a project is finished only when it runs reliably in production.

  • Tools of my own

    If there is no suitable tool for a task, I build one. Examples are plxr, a terminal for coding agents, and the firmware for my ESP32 display.

  • Planning

    Before I write any code, I set out in a specification what will be built and how. With a clear brief, even larger applications can be built in a few days.

  • Debugging

    When something breaks, I look at logs and measurements before I change anything. That way I know where the cause lies and do not have to guess.

  • Up-to-date stack

    I set up new projects with the current versions of their frameworks and keep them up to date. I avoid stopgaps that cause work later on.

  • Working with coding agents

    I run several coding agents in parallel and lead them like a small team: I provide the specification, hand out the tasks and check the results in review.

View CV
  1. NYO GmbHsince 01/2026
  2. Pocket Rocket GmbH10/2025–12/2025
  3. Plan Software GmbH2018–09/2025
  4. Kern GmbH2014–2018
  5. Personal projectssince 2008
  6. Umwelt-Campus Birkenfeld2009–2016
  7. Gymnasium am Steinwald1998–2008
All projects

plxr brings coding CLIs such as Claude Code, Codex, aider, Gemini and opencode together in one window. Every session appears as a tile; sessions waiting for an answer come first, with files, diff and terminal alongside.

  • The terminals keep running in a separate Go service, even when the window is closed.
  • Four skins restyle the whole window, each with its own icons.
  • Installers for macOS, Linux and Windows; updates are installed with a single click.
  • The source code is public on GitHub.

Built with Go, Wails, Next.js and TypeScript

plxr: CRT skin
All projects

  • FinForms

  • immosaar24

  • Van der Geldern

  • SoulMining

  • The Visual Designers

  • Unbrav

  • ander5

  • Select Immobilien

  • Baby made in BIR

  • BeTa Immobilien

Do you have a question about a project or would you like to talk tech?

[email protected]

Then write to me.

Write to me