Hey, I'm Carl!

I'm a proud dad. I play badminton, do paragliding and make my own pasta. I enjoy building software on the web platform. Currently I build with TypeScript and Go for the German Airforce.

I organize the Munich TypeScript meetup.

And yeah, my last name is Assmann.

Projects I'm Proud Of

tilly

A relationship journal app that helps me being a better friend. My take on how good web apps can and should feel.

intl

A typesafe internationalization library that does not require code generation

md-ai

A coding agent that runs in the CLI and stores the session as editable markdown

Blog Posts

I write about what I think, learn, do.

Nov 28 2025

The Two Trees in React

React encourages thinking about your UI as a tree. But there are two different trees that matter for understanding re-renders, and confusing them leads to performance problems and wasted effort.

#react

Oct 27 2025

A New Kind of Web App

Replicache removed the network from the critical path. Jazz removes it from the architecture. Local-first development that feels like Zustand and syncs like magic.

Oct 1 2025

Making TypeScript Errors Actually Helpful

When building my own typesafe i18n library, TypeScript's default errors became hard to work with. I learned how to create custom error messages that tell you exactly what's wrong and how to fix it.

View all posts

Latest Recipes

What I have been cooking recently.

Dec 14 2025