Software architecture · Development · Fractional CTO
Software that holds up when it matters.
I provide software architecture, custom development, and fractional CTO leadership for teams that need high-stakes systems built right the first time. No agency fluff, no junior hand-offs. Just senior engineering that scales.
>200transports
per day
per day
Non-emergency patient transport for the Red Cross, coordinated across Tyrol.
12×
ARR growth driven as CTO, from $100K to $1.2M
3
Platforms shipped from one codebase: desktop, web & mobile
Built, led & advised for
Austrian Red CrossRemove.TechROI Ventures
One partner across the whole stack of decisions.
From the first architecture sketch to the system running in production, and the leadership in between.
Most requested
Custom software development
Applications engineered for the requirements you actually have, not the ones an off-the-shelf product assumes. Built to be maintained, extended, and handed over cleanly.
01
Software architecture
Systems designed to scale: clear boundaries, sane data models, and pragmatic decisions that let you ship fast today without painting yourself into a corner tomorrow.
02
Technical consulting
An independent senior read on your stack, your roadmap, or that one decision the team keeps circling.
03
Fractional CTO
Technical leadership without the full-time hire: hiring, direction, and ownership of the hard calls.
04
Cloud & scalability
Infrastructure that grows with the business and stays calm under load, cost, and audit.
Selected work.
Two systems where the stakes were real, and so were the constraints.
Austrian Red Cross · Tyrol
Dispatch & logistics platform
Coordinating patient transport across nearly all of Tyrol.
Drawing on my own experience as a volunteer medic, I designed and built the dispatch system behind the Red Cross’s non-emergency patient transport across nearly all of Tyrol. It runs on desktop, web, and mobile, and turns a logistics-heavy operation into something a dispatcher can manage in real time.
>200/day
Transports coordinated
Tyrol
Region-wide coverage
ArchitectureFull-stack buildDomain expert
Remove.Tech
CTO · Scale-up
From $100K to $1.2M ARR, on architecture built to move fast.
As CTO at Remove.Tech I took ownership of the technical platform and led it through the growth phase that took the business from $100K to $1.2M ARR.
12×
ARR growth
$1.2M
ARR reached
CTO leadershipArchitectureTeam & hiring
How a project runs.
Agile in practice, not as a corporate slogan. I keep cycles short and feedback loops tight, so surprises stay rare.
01
Requirement analysis
I dig into the root of your problem and define your actual constraints before writing a single line of code.
02
Proposal & charter
A clear project charter: goals, non-goals, dates, and acceptance criteria both sides sign off on.
03
Iterative build
You see working software at every step, not status reports, so what ships is what you pictured.
04
Handover & care
Documented, maintainable, and supported: operations included once it’s live.
Who you'll work with
Marcel Juen: engineer, architect, and the person who ships it.
Raincoat Systems is my independent engineering practice. Based in Tyrol and frequently on the ground in Vienna, I work with no layers between you and the person building the system. The person you brief is the person who designs your architecture and writes your code: senior engineering without the overhead.
My background spans hands-on full-stack engineering, building mission-critical systems with real-world stakes, and leading a startup’s technical scale-up as CTO.
Modern tooling is part of how I keep that lean. I use AI to move faster on the routine work, so my attention goes to architecture, the edge cases, and the decisions that carry risk. The tools accelerate the work. The judgment is mine.
Marcel Juen, BScOwner · Raincoat Systems e.U. · Tyrol & Vienna
Beyond consulting
The right idea? I'm in.
Most of my work is consulting and fractional leadership. But now and then a founder shows up with an idea worth betting on, and when the conviction is there, I’ll step in as a technical co-founder and build it from the first commit.
Selective · Equity-aligned · Hands-on from day one
Let's build something that holds up.
Tell me what you’re trying to solve. I’ll tell you straight whether and how I can help.