Bits UI

Bits UI is the Svelte answer to Radix: accessible behaviour with no styles attached. It is the primitive layer under shadcn-svelte, which means most Svelte developers use it whether or not they installed it directly.

At a glance

Install	npm install bits-ui
Styling	none, fully agnostic
Svelte version	built for Svelte 5 runes
Used by	shadcn-svelte
MCP server	not published, but every doc page is markdown
License	MIT

Install

npm install bits-ui

What the code looks like

Namespaced components with addressable parts, so styling never fights the library.

<script lang="ts">
  import { Dialog } from "bits-ui";
  let open = $state(false);
</script>

<Dialog.Root bind:open>
  <Dialog.Trigger class="btn">Rename project</Dialog.Trigger>
  <Dialog.Portal>
    <Dialog.Overlay class="overlay" />
    <Dialog.Content class="panel">
      <Dialog.Title>Rename project</Dialog.Title>
      <Dialog.Description>This cannot be undone.</Dialog.Description>
      <Dialog.Close class="btn">Cancel</Dialog.Close>
    </Dialog.Content>
  </Dialog.Portal>
</Dialog.Root>

Documentation built for agents

Every documentation page is served as clean markdown, with a consolidated file at bits-ui.com/docs/llms.txt. There is no MCP server, but pointing an assistant at those files gets you accurate props without the usual hallucinated API surface.

Choose it if

• You are on Svelte 5 and want behaviour you can style from zero.
• You are building a Svelte design system and want a tested accessibility layer.

Look elsewhere if

• You want something styled today. shadcn-svelte is this library with a design on top.
• You are still on Svelte 4. Check version support before you install.