assistant-ui vs OpenUI
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
Open standard and toolkit for AI models to generate and stream live user interfaces.
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 OpenUI if you need…
- Developers adding AI-generated charts, forms, or tables to a web app
- Teams building chat assistants or copilots that answer with interactive UI
- React developers who want prebuilt chat layouts and component libraries
- Developers using LangChain or LangGraph agents that stream through AG-UI
Side-by-side
| assistant-ui | OpenUI | |
|---|---|---|
| Type | Library | Framework |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 12.9k | 14.7k |
| Setup difficulty | Intermediate | Intermediate |
| How you get it | Install with a package manager | Install with a package manager |
| Main language | TypeScript | TypeScript |
| Last code update | 4 days ago | 4 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.
OpenUI
OpenUI is a framework for building interfaces that an AI model generates on the fly. It defines a compact language, OpenUI Lang, that a model streams as it writes, and a renderer that turns that stream into live UI in React, Vue, Svelte, or Angular. You define a set of components, and OpenUI builds the instructions that tell the model which components it may use.
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
OpenUI
- Developers adding AI-generated charts, forms, or tables to a web app
- Teams building chat assistants or copilots that answer with interactive UI
- React developers who want prebuilt chat layouts and component libraries
- Developers using LangChain or LangGraph agents that stream through AG-UI
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
OpenUI
- MIT licensed and open source, with a published package set for several frontends
- Claims up to 67% fewer tokens than JSON for the same output (a figure from the README, not independently verified here)
- Streams output progressively, so the UI updates as the model writes
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
OpenUI
- People who only need a plain chatbot with text replies, since the project is built around generated UI
- Teams not using a supported frontend (React, Vue, Svelte, Angular) without extra integration work
- Anyone who needs a fully proven production track record, since the README does not describe production deployments
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
OpenUI
- The README is a broad overview; detailed API docs live on the external docs site
- Many packages and integrations make the right starting point unclear for newcomers
- Output quality depends on the model and on how well the component library is defined
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 initOpenUI
Scaffold a new chat app
npx @openuidev/cli@latest create --name genui-chat-appFrequently asked questions
What is the difference between assistant-ui and OpenUI?
assistant-ui: A TypeScript/React library for building AI chat interfaces in your app. OpenUI: Open standard and toolkit for AI models to generate and stream live user interfaces. assistant-ui suits react or next.js developers adding an ai chat panel to an existing app, while OpenUI suits developers adding ai-generated charts, forms, or tables to a web app.
Are assistant-ui and OpenUI free?
assistant-ui: Free and open source. OpenUI: Free and open source.
Is assistant-ui or OpenUI more popular?
OpenUI has more GitHub stars (14.7k) 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 OpenUI?
Other options people compare them with include CopilotKit, shadcn/ui, Radix Primitives, Base UI, LangChain.
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.