LUKAS
JELEN
Product builder · UX · Systems · AI-assisted development

I take products from a fuzzy idea to shipped reality — designing the UX, architecting the system, and building it fast with AI. Seventeen years across games, training software and FinTech.

Trusted by teams at
What I do for you

Idea → working prototype in days

AI-assisted development turns a rough concept into something you can click, test and show to users or investors — then iterate fast on real feedback.

The whole product, not just a slice

Research, UX, architecture and implementation are one continuous loop in my head, so nothing falls through the gaps between roles.

Senior product judgment

I decide what's worth building, keep it simple and performant, and know when the AI output is actually good — the scarce skill in AI-era software.

Delivery leadership when you need it

Seventeen years of shipping means I can also run the project, coordinate a team and keep the overview of how it all fits together.

Proof of method — the prototype that became a product

Contuere

Started asWealth Planner TodayContuere — financial software suite

The personal finance app I designed and built solo with AI in ten days outgrew itself. It is now Contuere: a local-first financial software brand at contuere.com, with a far deeper Wealth Planner and a second product alongside it. The free Local edition runs in your browser, needs no account, works offline, and keeps your financial data in a file on your own device.

Wealth Planner Live

Income, expenses, budgets and sinking funds, cash and investments backed by real market data — plus goals, retirement projections, a what-if optimization workspace and reports you generate on your device.

Trading Journal In development

Accounts, batches, trades, strategies and rules, journalled with the reasoning behind them — then measured by P&L, win rate, expectancy, drawdown and holding time.

Where it started

Wealth Planner — the original ten-day build

The first version is still live and unchanged: the prototype that proved the idea was worth turning into a product.

How I built it Using Cursor · In 10 days

Built with Vite + Vue — a full FinTech-style product surface, not a toy demo. AI gets you to working screens quickly, but the hard part is domain logic: market data integration, optimization models, retirement projections and charts that actually help decisions. That product judgment — knowing what to build, what to simplify and when the output is trustworthy — is what turns a prototype into something you'd use every day, and what made this one worth growing into a brand.

ViteVue
Open the original →
Open Contuere →
Proof of method — live & playable

Games Portal

A web-games portal I designed and built solo with AI, to show how fast I can ship polished, fast, browser-based software. Every game is a small demonstration of UX, performance and finish. Click any of them — they're live.

How I built it Using Cursor · In three days

Built with a modern stack — Vite + Vue, with Pixi.js for rendering. The first AI iterations are functional fast and cover a lot of ground, but that's the easy 80%. The value is in the last 20%: detailed, technically sound prompting to get real UX polish, and optimization so every game runs smoothly at high performance on desktop, tablet and mobile alike. That judgment about what "good" means — and how to steer AI toward it — is the part that doesn't come for free.

ViteVuePixi.js
Open Games Portal →
What I'm building now

Four products I'm actively shipping: two as freelancer and two as self-employed builder.

Freelance · FinTech live product

mylifeplan.ch

A user-facing FinTech product I lead as product & delivery owner — turning financial planning into something people can actually navigate.

Visit mylifeplan.ch →
Freelance · CRM B2B product

NG21

A CRM platform for financial advisors — architecture, UX and delivery. Not public, but happy to walk through the approach and results in a conversation.

Ask me about it →
Self-employed · developer tooling

ORAKEL (Codename)

A shot at software's oracle problem. ORAKEL builds a living behavioral model of what a system actually does (the IS model) and compares it against a SHOULD-BE model derived from the prose humans wrote about it.

Ask me about it →
Self-employed · puzzle game

Enliven

A puzzle game I am building in my own engine using C++, with release planned on Steam.

Ask me about it →
Work with me

Have a product you want built well and shipped fast? Tell me what you're trying to make and where it's stuck — I'll tell you honestly how I'd approach it.

Berlin, Germany · remote-first (17 yrs) · German (native) / English (fluent)