Integrate Cedar-OS with Mastra

Cedar-OS is an open-source agentic UI framework designed specifically for building the most ambitious AI-native applications. We built Cedar with Mastra in mind.

Should you use Cedar?

There are a few pillars we care about strongly that you can read more about here :

1. Developer experience

Every single component is downloaded shadcn-style – You own all the code and can style it however you want
Works out of the box – Just drop in our chat component, and it’ll work
Fully extensible - Built on a Zustand store architecture that you can customize completely. Every single internal function can be overridden in one line.

2. Enabling truly AI-native applications

For the first time in history, products can come to life. We want to help you build something with life.

Spells - Users can trigger AI from keyboard shortcuts, mouse events, text selection, and other components
State Diff Management - Give users control over accepting/rejecting agent outputs
Voice Integration - Let users control your app with their voice

Quick Start

Set up your project

Run Cedar’s CLI command:


npx cedar-os-cli plant-seed

If starting from scratch, select the Mastra starter template for a complete setup with both frontend and backend in a monorepo

If you already have a Mastra backend, use the blank frontend cedar repo option instead.

This will give you the option to download components and download all dependencies for Cedar. We recommend at least downloading one of the chat components to get started.

Wrap your app with CedarCopilot

Wrap your application with the CedarCopilot provider to connect to your Mastra backend:


import { CedarCopilot } from 'cedar-os';
 
function App() {
	return (
		<CedarCopilot
			llmProvider={{
				provider: 'mastra',
				baseURL: 'http://localhost:4111', // default dev port for Mastra
				apiKey: process.env.NEXT_PUBLIC_MASTRA_API_KEY, // optional — only for backend auth
			}}>
			<YourApp />
		</CedarCopilot>
	);
}

Configure Mastra endpoints

Configure your Mastra backend to work with Cedar by following the Mastra Configuration Options .


import { registerApiRoute } from '@mastra/core/server';
 
// POST /chat
// The chat's non-streaming default endpoint
registerApiRoute('/chat', {
	method: 'POST',
	// …validate input w/ zod
	handler: async (c) => {
		/* your agent.generate() logic */
	},
});
 
// POST /chat/stream (SSE)
// The chat's streaming default endpoint
registerApiRoute('/chat/stream', {
	method: 'POST',
	handler: async (c) => {
		/* stream agent output in SSE format */
	},
});

Add Cedar components

Drop Cedar components into your frontend – see Chat Overview .

Your backend and frontend are now linked! You’re ready to start building AI-native experiences with your Mastra agents.

More information

Check out the detailed Mastra integration guide for more configuration options (or for manual installation instructions if something goes wrong)
Explore Mastra-specific optimizations and features we’ve built
- Seamless event streaming - Automatic rendering of Mastra streamed events
- Voice endpoint support - Built-in voice backend integration
- End-to-End type safety - Types for communicating between your app and Mastra backend
Join our Discord! We’re excited to have you :)