assistant-ui vs Radix Primitives
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
A TypeScript/React library for building AI chat interfaces in your app.
Open source · MIT
Unstyled, accessible React UI components for building your own design system.
The short answer
Choose assistant-ui if you need…
- React or Next.js developers adding an AI chat panel to an existing app
- Teams that want to style chat UI with their own design system or shadcn/ui
- Developers who need tool-call rendering or inline human approval in a chat
- Projects already using the Vercel AI SDK or LangGraph
Choose Radix Primitives if you need…
- Developers building a custom design system who want accessible base components
- Teams adding accessible interactive widgets to an existing web app incrementally
- React developers who want to control styling themselves
Side-by-side
| assistant-ui | Radix Primitives | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 12.9k | 19.5k |
| Setup difficulty | Intermediate | Intermediate |
| How you get it | Install with a package manager | Clone and build from source |
| Main language | TypeScript | TypeScript |
| Last code update | 4 days ago | 22 days ago |
What each one is
assistant-ui
assistant-ui is an open-source TypeScript and React library for building chat interfaces like ChatGPT inside your own web app. It provides composable chat pieces such as threads, messages, and a composer, and connects them to backends like the Vercel AI SDK, LangGraph, or your own custom backend.
Radix Primitives
Radix Primitives is a collection of low-level user interface components, such as building blocks for menus, dialogs and similar controls. The README describes a focus on accessibility, customization and developer experience. Teams can use them as the base layer of a design system or adopt them one at a time.
Best for
assistant-ui
- React or Next.js developers adding an AI chat panel to an existing app
- Teams that want to style chat UI with their own design system or shadcn/ui
- Developers who need tool-call rendering or inline human approval in a chat
- Projects already using the Vercel AI SDK or LangGraph
Radix Primitives
- Developers building a custom design system who want accessible base components
- Teams adding accessible interactive widgets to an existing web app incrementally
- React developers who want to control styling themselves
Strengths
assistant-ui
- Composable primitives let you build custom chat layouts instead of using one fixed component
- Includes streaming, attachments, markdown, and accessibility features according to the README
- Typed TypeScript APIs for runtimes, tool schemas, and message parts
Radix Primitives
- Stated focus on accessibility, customization and developer experience
- Can be adopted incrementally rather than all at once
- Open source under the MIT License with a large community following (about 19,400 stars)
Not ideal for
assistant-ui
- People who want a finished chat app without writing any code, since it is a library for developers
- Projects not using React, because the library is built for React and TypeScript
- Teams that need a single drop-in component with no customization, since the README describes composing primitives instead
Radix Primitives
- People who want ready-made, styled components out of the box, since the README describes these as low-level primitives
- Non-developers looking for a finished website or app builder
- Projects that do not use React, since the topics and description point to React
Trade-offs
assistant-ui
- Requires React and TypeScript knowledge, so it is not beginner-friendly for non-developers
- The README is truncated and does not fully document every backend or setup detail
- Being a library, you still need to supply and pay for your own model provider and backend
Radix Primitives
- Low-level by design, so you must add your own styling and layout work
- The README is short and points to external docs for component details
- No formal release is listed, so you need to check the changelog for versioning
Getting started
assistant-ui
Create a new project with the CLI
npx assistant-ui@latest createAdd to an existing project with the CLI
npx assistant-ui@latest initRadix Primitives
Install pnpm
npm install -g pnpmInstall dependencies
pnpm installFrequently asked questions
What is the difference between assistant-ui and Radix Primitives?
assistant-ui: A TypeScript/React library for building AI chat interfaces in your app. Radix Primitives: Unstyled, accessible React UI components for building your own design system. assistant-ui suits react or next.js developers adding an ai chat panel to an existing app, while Radix Primitives suits developers building a custom design system who want accessible base components.
Are assistant-ui and Radix Primitives free?
assistant-ui: Free and open source. Radix Primitives: Free and open source.
Is assistant-ui or Radix Primitives more popular?
Radix Primitives has more GitHub stars (19.5k) than assistant-ui (12.9k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to assistant-ui and Radix Primitives?
Other options people compare them with include CopilotKit, shadcn/ui, Base UI, Headless UI, Evergreen.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.