Hydraloop Device Manager
Full-stack IoT platform for monitoring and controlling Hydraloop water recycling systems. Real-time dashboards, device provisioning and remote diagnostics, built on the PEAN stack.
Software Engineer · Leeuwarden, NL
Stijn Timmerman
Full-stack engineer specialised in connected products, web apps, AI agents and DevOps. From IoT platforms to self-hosted LLM tooling, I build it.
Portfolio
Projects.
From IoT platforms at Hydraloop to self-hosted AI tooling and my own web shops.
hydraloop.com
Hydraloop's public marketing and lead platform, built as headless WordPress with a fully custom PHP frontend. Features an agentic AI chatbot (Blu) that recommends products and schedules appointments, an interactive 3D product configurator, a custom translation system on the ChatGPT API serving the site in six languages, and lead scoring with CRM integration.
hydraloop.com →Hydraloop App
Mobile app that lets users monitor and control their Hydraloop water recycling system. Available on iOS and Android.
Professional
3D product configurators
Interactive product configurators for the Hydraloop H300 and H600: a real-time Three.js 3D model where you switch colours and options and start a request right away. I previously built the Upfall shower configurator on the same stack.
hydraloop.com/h300 →VPS Ops Agent
Self-hosted observability agent with a tool-calling LLM that inspects my VPS read-only. Containers, services, logs and resources, queried in natural language. Runs on Ollama Cloud behind an auth gateway.
The Council
An AI council in which five models, each with its own perspective, debate a question chaired by a neutral moderator and vote in multiple rounds until they reach unanimity. The entire deliberation streams live to the browser.
Steil Digital
Web agency I am co-founding. Marketing site with a headless CMS, lead forms with email notifications and a full DTAP pipeline from git to production, self-hosted on my VPS.
steildigital.nl →Kwanton
E-commerce shop built with Medusa.js v2. Custom Next.js storefront with Stripe integration, product collections and an admin dashboard.
kwanton.nl →Bij Stijn
Personal dashboard with a dark-themed UI. Flutter web app hosted as a static site behind a Caddy reverse proxy.
app.stimmerman.nl →Freelance
Elisateigeler.nl
Design and build of the portfolio site for creative designer Elisa Teigeler: a fast, responsive one-page site with custom animations, self-hosted on my VPS.
elisateigeler.nl →Play a game of chess
Anonymously against a random visitor. Pick a name, join the queue and play. Casual, no account.
click to playCareer
Work experience.
Grew from working student to medior software engineer at Hydraloop.
Jan 2026 — present
Medior Software Engineer
Hydraloop Systems
Full-stack owner of the Hydraloop Device Manager (HDM) IoT platform, the architecture of the app and website, and the integration of AI systems. Working with the PEAN stack daily.
Jul 2023 — Jan 2026
Junior Software Engineer
Hydraloop Systems
Worked mainly on the Hydraloop Device Manager (HDM) IoT platform and the Hydraloop smartphone app, alongside 3D product configurators in TypeScript and Three.js.
Oct 2022 — Jun 2023
Working Student Software Engineering
Hydraloop Systems
Jan 2023 — Jul 2023
Graduation internship
Achmea
Built a learning platform about big data: the benefits, drawbacks and ethical considerations.
Jan 2022 — Jul 2022
Innovation Development internship
GGZ Friesland
Developed a VR experience that helps relatives understand what a psychotic episode feels like.
Jan 2019 — Jul 2021
Tutor in Maths, Chemistry & English
TopTutors
Education
Education.
2019 — 2023
BSc Communication & Multimedia Design
NHL Stenden
2017 — 2019
ICT (first-year diploma)
NHL Stenden
About
Who I am.
I'm Stijn, a full-stack engineer from Leeuwarden, the Netherlands, with a background in Communication & Multimedia Design. I've been at Hydraloop since 2022, growing from working student to medior software engineer, and I'm the full-stack owner of the Hydraloop Device Manager IoT platform.
My deepest experience is with the PEAN stack: PostgreSQL, Express, Angular and Node.js, which I build with daily at Hydraloop. I also run my own VPS where I self-host everything: Docker containers, databases, Caddy reverse proxies and CI/CD pipelines. I love hands-on DevOps and owning the whole picture, from idea to production.
Frontend
Angular, React, Next.js, Flutter, TypeScript, Tailwind CSS
Backend
Node.js, Express, PostgreSQL, Prisma, Medusa.js, REST, WebSocket
DevOps
Docker, Caddy, Linux, SSH, CI/CD, Cloudflare
AI & More
LLM agents, Ollama, tool-calling, IoT/MQTT, Git, Stripe, Bash
Contact