Product Designer & Builder

I help companies, from garage startups to corporations like T-Mobile and Vodafone, improve their mobile & web apps by simplifying them. It’s not easy to make things simple, but I have 17 years of experience doing that 🙂. Bridging the divide between design and development (and management) is also my forte, and it goes a long way.

Medable — Study Participant App Concept: a row of mobile screens from the redesigned clinical-trial app

What people say

“He works across visual design, UX and front-end, and takes his own work from idea to shipped rather than handing off mockups. That combination is genuinely rare, and ideal for startups.”

– Neil Berkman
CTO
at Enaia

“One of the most thoughtful product design leaders I’ve had the pleasure of working with throughout my career.”

– Joshua Bryant
Director of Product Design
at Medable

“It’s rare that you come across exceptional talent like Josef. He showed outstanding product design skills and a deep understanding of product strategy.”

– Timon Reinhardt
Lead PO Smart Home
at T-Mobile/Deutsche Telekom

“Josef is a thoughtful, skillful design lead who combines mastery of his craft with perceptive analysis, a focus on users, and excellent communication.”

– Andrew Purcell
Senior Director, Digital UX & Design
at Marriott International

“Josef is a bright holistic design thinker. He is able to break down the brief or problem into smaller clear parts, and provides clear paths to take.”

– Sina Mossayeb
Chief Design Officer
at Medable

“His many years of experience and ability to get deep into the technical aspects of work was an immense asset to our work!”

– Chris Meierling
Director of Service Design
at Medable

“I was particularly impressed by Josef’s ability to remove nonessential complexity from the product, which led to extraordinary results in user testing.”

– Timon Reinhardt
Lead PO Smart Home
at T-Mobile/Deutsche Telekom

More testimonials

My Process

I believe good products come from thorough understanding and structured process. Thorough understanding of problem at hand, the industry, the users, the business side. And then applying this knowledge throughout logical steps, call it Design Thinking or whatever you like; the point is to not fool yourself.

Read about my process

Selected work

Medable Clinical Trials

Medable runs decentralised clinical trials. I led the redesign of their participant app – used globally and translated into 110 languages – focusing on the self-reporting forms participants use instead of visiting their physician.

The constraint was brutal: these forms have collected data for 20–30 years, and any change, however tiny, can bias the data and invalidate a trial (average cost $2.6B, average duration 12 years). Yet a full paper form is unusable on a phone. We worked closely with scientists to find the narrow middle ground between user needs and scientific validity. It might be the most sensitive app design work there is.

Medable participant app — self-reporting form redesigned for mobile

Medable — overview of redesigned clinical-trial app screens

T-Mobile Smart Home

A new smart-home product for Deutsche Telekom / T-Mobile – a long-term project that started by introducing a design system, then rebuilding the whole product on top of it.

It revolved around “stories” – everyday situations like “turn on the lights when I come home” that work out of the box with almost zero setup. A deliberate departure from rivals that offer endless automation but no meaningful defaults.

Soul Mate

A dating app built around date ideas rather than photos: you first pick an activity you enjoy, then find someone to share it with.

Soul Mate dating app — date ideas screen

Soul Mate dating app — collage of screens

Advanced prototyping

I’m a big believer in advanced prototyping – simple but functional apps that focus on the one feature in question. It’s far cheaper to hit dead ends here than in development.

This T-Mobile prototype uses Dialogflow for speech recognition (note this is pre-AI era) and Firebase to talk between two prototypes – a phone app and a desktop app that simulates a room in an apartment. All built in Framer.

Code

I write code so I understand what I’m working with – what’s easy, what’s hard, and what developers need from me. Mostly Elixir, plus Rust, Swift and TypeScript/React.

I build my own products – mobile & web apps – alongside freelance work, often wrestling with high-concurrency problems (too many people → server crash):

Sorted – event registrations that don’t crash under heavy load. Fully agentic event management.
Stock Sorted – Shopify app for shared inventory across stores; Shopify can’t handle it natively, a textbook concurrency problem. (why it’s harder than it looks)
nutritious.love – AI calorie tracker: scan food, get nutrition-change recommendations, and more.
HabitPass – iPhone app that builds a language-learning habit by locking out social media.
Tideman – a tool that helps students test their implementation of the “final boss” algorithm from Harvard’s CS50.
francis_template – open-source Elixir package for file-based HTML templating in the Francis web framework (this very site runs on it).
francis_sqlite – open-source SQLite integration for the Francis Elixir web framework.

More of my work is on GitHub.

Build a Twitter clone on the BEAM A step-by-step Chirp tutorial in Elixir + Francis – realtime, multi-user, zero external infrastructure.