kumo.ui
← back / index

case · 01 / TS · React · Vite

kumo.ui

headless design system · 47k weekly downloads

year

2025 — present

role

founder · lead engineer

client

open-source · MIT

stack

TypeScript · React 19 · Radix

an unstyled, accessibility-first component library that ships under 12kb gzipped — the headless layer the team kept rebuilding at every job got carved out and given a name.

ch · 01

the problem

design teams kept hitting the same wall: shadcn was opinionated, radix-only was bare, and chakra/mui were too heavy. nothing fit a calm, typographic, design-system-first workflow.

ch · 02

the cut

47 primitives, zero runtime CSS, full RSC support, polymorphic `as` prop with strict generics, focus-trap and aria wiring tested against axe + screen-reader matrices.

ch · 03

the ship

12kb gzipped core. tree-shakes to ~2kb for a single primitive. dual ESM/CJS. ships with codemods for v0→v1 migration.

/ outcomes

weekly downloads

47k

bundle (core)

12kb

github stars

3.8k

a11y score

100/100

kumo.ui · 1
kumo.ui · 2
kumo.ui · 3

/ stack

TypeScriptReact 19RadixVitetsupVitest

/ links