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Headless accessible Svelte components · by Hunter Johnston (huntabyte)

Bits UI

Headless, accessible Svelte components with render delegation and data-attribute styling, maintained by Hunter Johnston and used as the base of shadcn-svelte.

Visit bits-ui.com ↗ Alternatives Open source Open source
Bits UI homepage
§1

Overview

Bits UI is a headless component library for Svelte focused on developer experience, accessibility and full styling control. Most components ship completely unstyled except where styles are required for core behaviour, and there are no CSS resets. You pass classes directly or target data-* attributes that expose component state.

Accessibility is built in: WAI-ARIA compliance, keyboard navigation, focus management and screen reader support. Components are composable primitives with render delegation for custom elements, chainable events and override-friendly defaults. The date and time components take inspiration from React Spectrum, the API design from Radix, and the internal architecture from Melt UI.

Bits UI is built and maintained by Hunter Johnston, with design support from Bitworks Studio. It underpins shadcn-svelte, so its release cadence directly affects that project. If you want the same behaviour with ready-made styles, start with shadcn-svelte; if you are building your own design system, use Bits UI directly and add your own class names or data-attribute selectors.

§2

Pricing and plans

Plan Price What you get
Open source Free MIT licence

No paid tier.

Source: bits-ui.com/docs/introduction · prices as published, excluding tax.

§3

What it does

Headless components
Dialog, Popover, Menu, Select, Combobox, Tabs, Slider, Calendar, DatePicker and more.
Render delegation
Render primitives as your own elements or components.
Date and time
Accessible calendar, date field and range components.
Typed API
Full TypeScript coverage with stable, predictable APIs.
§4

Strengths and limitations

Strengths

  • Most complete headless library for Svelte 5
  • Strong date and time components
  • Foundation of shadcn-svelte
  • No styling assumptions

Limitations

  • Svelte only
  • You write all styles yourself
  • Largely maintained by one person, so bus factor is low
  • Complex widgets still need your own styling work before they look finished
§5

Who it suits

Good for

  • Svelte teams building a design system
  • Apps needing accessible date pickers in Svelte

Look elsewhere if

  • Teams wanting styled components out of the box (use shadcn-svelte or Skeleton)
  • Non-Svelte projects
§6

Alternatives to Bits UI

Tool From Free option Stages
shadcn-svelte Copy-in Svelte component collection and CLI
— Open source
Chakra UI Styled React component library
— Free tier
shadcn-vue Copy-in Vue component collection and CLI
— Open source
shadcn/ui Copy-in React component collection and registry CLI
— Open source
Radix UI Unstyled accessible React primitives
— Open source
HeroUI Styled React component library (formerly NextUI)
— Free tier

All UI component libraries →

§7

Questions

Is Bits UI styled?

No. Components are headless; shadcn-svelte provides a styled layer on top.

Who maintains Bits UI?

Hunter Johnston, with design support from Bitworks Studio and community contributors.

Bits UI or Melt UI?

Bits UI offers component-style primitives and cites Melt UI as the inspiration for its internals.

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