In motion
I think better when I've moved — so most days I do, across a few different things rather than just one.
Senior Software Engineer
To build & to teach & to make software that ages well.
Manifesto
I build software the way I'd want it built for me: readable, honest, and small enough to fit in someone's head. The job isn't to ship the cleverest abstraction — it's to leave the codebase better than I found it for whoever inherits it next.
After a decade between consultancies, healthtech, and side projects, what sticks is this: good engineering is a long game. Patterns matter less than the discipline to read what you wrote yesterday and ask if it's still the simplest thing that works.
Lately I'm fascinated by what AI changes about the craft — not as autocomplete, but as a collaborator. Most of what you're reading on this site was written next to one.
Career
A decade delivering software — from consultancy delivery floors to connected-care systems. My foundation is durable, universal craft; .NET just happens to carry most of my stack. The short version below; the full story is one click deeper.
Explore the full career Side projects
Things I build after hours — for the fun of it, or because I had a problem worth solving properly. Every decision is mine, and I write down what each one cost.
- 01
Aura
2026–PresentThe app I built to work with my AI assistants from my phone. Each brings its own identity, skills, workspace and conversations together, with agents on my server that can work with files and applications.
- .NET 10
- React
- PWA
- SQLite
- Agent adapters
- 02
felixdiez.com
2026The site you are reading. A content-driven Astro build with no UI framework — hand-rolled components, CSS-only scroll animations, and content collections for the blog, bookshelf and knowledge notes, all driven from a single editable content file.
- Astro
- TypeScript
- Content Collections
- RSS
- 03
Soma Tracker
2026–PresentA personal fitness tracker — weigh-ins with a trend I trust, a guided workout player, a weekly plan — built solo instead of picking one of the many apps already out there. Since September 2026 a bathroom scale feeds it on its own: a Raspberry Pi hears the reading over Bluetooth, a small relay passes it to an AI assistant, and the assistant decides what to log.
- .NET 10
- SQLite
- Python
- Raspberry Pi
- Bluetooth LE
- Tailscale
About me
When the laptop closes I'm in Rivas-Vaciamadrid, on the southeastern edge of Madrid — close enough to the city, far enough to hear it go quiet. The Southeast Regional Park starts at the door — low hills, pine woods and scrub, the old gravel-pit lagoons, and the Manzanares and Jarama rivers meeting just downstream. I traded a few minutes of commute for room to breathe.
Home is a family with two daughters — the eldest 2 years, the youngest just 5 months. They're the reason I guard the hours after work as fiercely as the ones inside it.
Off the clock I read
Sci-fi, a few novels, and the odd book that nudged how I think — like Dune and Los Asquerosos.
The rest of the shelf → Contact
Let's talk.
Best place is email — [email protected]. I read everything, and reply to most things within a couple of days.
Blog
- The Scale Broadcasts. The Agent Decides.
- There Are a Million Fitness Apps. I Built My Own Anyway.
- The Code Worked. The Design Was Still Wrong.
All writing →