Follow the steps below to get started with Cosmic to power content for your Bun application.

Create folder and install Bun and React Dom

mkdir cosmic-bun
cd cosmic-bun
npm init
npm i bun -g
npm i react-dom

Install the Cosmic JavaScript SDK

Install the Cosmic JavaScript SDK in the location of the codebase.

npm i @cosmicjs/sdk

Add an Object type in the Cosmic dashboard

Log in to the Cosmic dashboard and create a new Blog Posts Object type in a new or existing Project with the following metafields:

  1. Image: Image type with key image
  2. Content: Rich text with key content

Blog model

Add content

Add a few blog posts to get some content ready to be delivered.

Create a new file index.tsx and add the following:

// index.tsx
import { renderToReadableStream } from 'react-dom/server';
import { createBucketClient } from '@cosmicjs/sdk';

const cosmic = createBucketClient({
  bucketSlug: process.env.BUCKET_SLUG || '',
  readKey: process.env.BUCKET_READ_KEY || '',

type PostType = {
  title: string,
  metadata: { image: { imgix_url: string }, content: string },

function Home({ posts }: { posts: PostType[] }) {
  return (
      {posts?.map((post: PostType) => {
        return (
          <div key={post.title}>
            <div dangerouslySetInnerHTML={{ __html: post.metadata.content }} />

const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const { objects: posts } = await cosmic.objects
        type: 'blog-posts',
    const stream = await renderToReadableStream(<Home posts={posts} />);
    return new Response(stream, {
      headers: { 'Content-Type': 'text/html' },

console.log(`Listening on ${server.url}`);

Add your Cosmic API keys

In a new file titled .env.local add the following environment variables and make sure to switch out the values with your Cosmic API keys found in Project / API keys.

# .env.local

Start the app

Start your app with the following command, go to http://localhost:3000, and see your blog posts. Note: we are using bun which enables environment variable reading without a separate package and the ability to use ES6 imports.

bun index.tsx