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Frontend Engineer — Based in Berlin

Interfaces that feel
inevitable.

I build fast, considered product interfaces for teams who care about the details most people never notice.

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Three projects, in depth

Each shipped to production, each with a real constraint that shaped the outcome.

Fintech · Design System
Ledger — Component System

A 140-component design system built for a banking dashboard used by 40,000 analysts daily. Rebuilt the table virtualization layer to cut render time by 70%.

E-commerce · Performance
Fernweg — Checkout Rebuild

Rebuilt a checkout flow from scratch after the old one was losing 12% of carts to load time. New flow ships in under 400kb and converts 18% higher.

Developer Tools · Motion
Circuit — Docs Site

Documentation site for a hardware SDK. Interactive code samples run in-browser via a WASM sandbox I built from scratch over one long winter.

Everything else

Arvo — Landing Page

Marketing site, 2025

Nordlys — Brand Site

Full rebuild, 2025

Palette — Internal Tool

Design tooling, 2024

Wayfind — Mobile Web

Navigation app, 2024

Ten years, one obsession

I've spent the last decade on the same problem: making interfaces that feel like they couldn't have been built any other way. Not flashy — inevitable.

Most of that time was spent on teams shipping to millions of users, where a 100ms delay is a business problem, not an engineering footnote.

10
Years shipping
40+
Products launched
3
Design systems built
Get in touch

Have something worth building?

hello@kairenner.example