assistant-ui vs CopilotKit
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
A TypeScript toolkit for building chat and generative UI on top of AI agents in web, mobile, and chat apps.
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 CopilotKit if you need…
- Developers adding an AI assistant or agent interface to a React or Next.js app
- Teams who want one agent backend to serve a web app, a mobile app, and Slack or Teams
- Projects that need agents to ask users for confirmation or edits before continuing
- Developers building chat interfaces that render custom UI components from tool calls
Side-by-side
| assistant-ui | CopilotKit | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 12.9k | 38.5k |
| 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.
CopilotKit
CopilotKit is an SDK for building applications where AI agents interact with users through a interface. It provides pieces such as a chat UI, shared state between agents and components, generative UI that agents can render at runtime, and human-in-the-loop prompts that pause an agent for user input. The README says the same agent can be served to React, Angular, Vue, React Native, and Slack or Microsoft Teams. The project is maintained by the company behind the AG-UI Protocol.
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
CopilotKit
- Developers adding an AI assistant or agent interface to a React or Next.js app
- Teams who want one agent backend to serve a web app, a mobile app, and Slack or Teams
- Projects that need agents to ask users for confirmation or edits before continuing
- Developers building chat interfaces that render custom UI components from tool calls
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
CopilotKit
- Covers several frontends (React, Angular, Vue, React Native) and chat channels from one agent backend, per the README
- Built on the AG-UI Protocol, which the README says is adopted by several large framework vendors
- Permissive MIT license with an active repository and a large star count
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
CopilotKit
- Non-developers looking for a ready-made app; the README targets people writing code
- Projects that do not use JavaScript or TypeScript frontends, since the listed frameworks are JS-based
- Teams who want a fully self-contained product without integrating an agent framework of their own
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
CopilotKit
- The README is partly a marketing overview; several features (Channels for Discord/WhatsApp, Vue quickstart) are listed as coming soon or only partly supported
- Some advanced features (rich threads, memories, analytics) belong to a separate hosted or self-hosted product called CopilotKit Intelligence, which may have its own plans
- Setup depends on your agent framework and frontend stack, so the learning curve is non-trivial
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 initCopilotKit
Set up with your coding agent (run from your project root)
npx --yes copilotkit@latest onboard startInstall agent skills for your coding agent
npx copilotkit@latest skills installFrequently asked questions
What is the difference between assistant-ui and CopilotKit?
assistant-ui: A TypeScript/React library for building AI chat interfaces in your app. CopilotKit: A TypeScript toolkit for building chat and generative UI on top of AI agents in web, mobile, and chat apps. assistant-ui suits react or next.js developers adding an ai chat panel to an existing app, while CopilotKit suits developers adding an ai assistant or agent interface to a react or next.js app.
Are assistant-ui and CopilotKit free?
assistant-ui: Free and open source. CopilotKit: Free and open source.
Is assistant-ui or CopilotKit more popular?
CopilotKit has more GitHub stars (38.5k) 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 CopilotKit?
Other options people compare them with include shadcn/ui, Radix Primitives, Base UI, LangGraph, Tambo.
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.