Karl Koch is an English-Danish designer and developer, and a founding Design Engineer at DuckDuckGo. Working across design and engineering, he builds digital products from their earliest interactions through to the details that make them feel polished. At DuckDuckGo, he is developing the company’s Design Engineering practice and has established principles for shared ownership, production workflows, and maintaining quality as the team grows.

Koch’s selected work includes Kernel UI, an open-source design system of semantic web components; improvements to motion and transitions in DuckDuckGo’s iOS browser; and Search Assist, an AI-assisted answer experience for DuckDuckGo Search, where he led product design and frontend development. He also designed and engineered Working Sets, an independent iOS app for tracking exercise sets.

Alongside client and product work, Koch shares writing, talks, and practical resources for design engineers. His offerings include d×e, a course and toolkit, and KK Sans, KK Serif, and KK Mono, typefaces he is making and using. He also provides free portfolio reviews, mentoring and career advice, and project briefing sessions.