Senior Software Engineer

To build & to teach & to make software that ages well.

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.

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.

  1. 2022 Tunstall Healthcare Senior Software Engineer · Aug 2022 — Present Current
  2. 2018 Minsait (Indra) Software Developer · Jun 2018 — Aug 2022
  3. 2016 everis (NTT Data) Junior Consultant · Nov 2016 — Jun 2018
Explore the full career
  1. 01

    Aura

    2026–Present

    A personal agentic LLM assistant platform, built from scratch. One shared core runs agents through pluggable adapters (Claude Code, Codex CLI) and reaches you across web, voice and messaging. .NET 10, hexagonal architecture, API-first, ADR-driven.

    • .NET 10
    • Blazor
    • Hexagonal Arch
    • OpenAI
    • SQLite
    Read the case study
  2. 02

    felixdiez.es

    2026

    The 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
    Read the case study
View full portfolio →

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 3 months. They're the reason I guard the hours after work as fiercely as the ones inside it.

In motion

I think better when I've moved — so most days I do, across a few different things rather than just one.

  • CrossFit / functional
  • Calisthenics
  • Running
  • Cycling
  • Pádel
  • Football
  • Swimming

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 →

Let's talk.

Best place is email — [email protected]. I read everything, and reply to most things within a couple of days.