How to run a Freestyle sandbox

You can clone this repo and update your credentials to run locally.

Freestyle is a cloud platform for running AI-generated code in isolated sandboxes. Let’s walk through the process of getting a basic application running inside a Freestyle sandbox.

Why use Freestyle as your sandbox provider?

A single API key is all you need to get started.
A runtime hint config option (node/python) lets you match your workload.
Lightweight and fast to get a sandbox running.

Let’s see how we can easily run a basic Vite app inside of a Freestyle sandbox.

Let’s start by creating a new Next.js project

Run this command in your terminal:

npx create-next-app@latest freestyle-basic

You can use all of the defaults when prompted.

Create an .env file

Once it has been created, be sure to create an .env file to add your necessary credentials to.

FREESTYLE_API_KEY=your_freestyle_api_key

Install ComputeSDK and the Freestyle provider

ComputeSDK ships as a small core package plus one package per provider, so you only install what you use.

cd freestyle-basic
npm install computesdk @computesdk/freestyle

Create or log in to your Freestyle account

Create a Freestyle account or log in here.
Create an account, then generate an API key from your Freestyle dashboard.

Save these values in your .env file.

FREESTYLE_API_KEY=your_freestyle_api_key

Now we’ll move on to creating the actual sandbox logic

We need to create the API route to create the sandbox

Import the freestyle factory from @computesdk/freestyle and pass it your credentials. compute.sandbox.create() provisions a sandbox on Freestyle.
Create a new route.ts file in app/api/sandbox and paste the following code:

// app/api/sandbox/route.ts
import { NextResponse } from 'next/server';
import { freestyle } from '@computesdk/freestyle';

const compute = freestyle({
  apiKey: process.env.FREESTYLE_API_KEY,
});

export async function POST() {

  const sandbox = await compute.sandbox.create();

  return NextResponse.json({
    sandboxId: sandbox.sandboxId,
  });
}

Next, we’ll edit the page.tsx file

We’ll keep it simple and just add one button to run our sandbox test with.
Replace the content on Page.tsx with this code:

// app/page.tsx
'use client';

export default function Home() {
  const createSandbox = async () => {
    const res = await fetch('/api/sandbox', { method: 'POST' });
    const data = await res.json();
    console.log(data);
  };

  return (
    <div className="flex min-h-screen flex-col items-center justify-center p-24">
      <h1 className="mb-8 text-4xl font-bold">ComputeSDK Sandbox Test</h1>
      <button
        className="rounded bg-blue-500 px-4 py-2 font-bold text-white hover:bg-blue-700"
        type="button"
        onClick={createSandbox}
      >
        Create Freestyle sandbox
      </button>
    </div>
  );
}

Now, our first test

Run npm run dev in your terminal to start the dev server.
Open localhost:3000
Click the button on the main page.

Then check your Freestyle dashboard.
You should see a new sandbox created!

Success!

You’ve successfully created your first Freestyle sandbox

If you want to use another sandbox provider like E2B or Daytona, swap the import and factory call — install @computesdk/e2b and use import { e2b } from '@computesdk/e2b' instead, with that provider’s own credentials. The rest of your code (runCommand, filesystem, getUrl) stays the same — that’s the point of the universal Sandbox interface.

Making changes within the sandbox

Now, let’s take the next step and run a primitive Vite app inside of our sandbox as an example of what we are able to do within the sandbox itself.

Update /api/sandbox/route.ts

Add the following to your app/api/sandbox/route.ts file directly below this in your code:

const sandbox = await compute.sandbox.create();

Create a basic Vite app inside our sandbox subfolder

// Scaffold Vite React app
await sandbox.runCommand('npm create vite@5 app -- --template react');

Use the writeFile method

Customize the vite.config.js so we can access the local dev server.

// Custom vite.config.js to allow access to sandbox at port 5173
  const viteConfig = `import { defineConfig } from 'vite'
  import react from '@vitejs/plugin-react'

  export default defineConfig({
    plugins: [react()],
    server: {
      host: '0.0.0.0',
      port: 5173,
      strictPort: true,
      hmr: false,
      allowedHosts: ['localhost', '127.0.0.1'] // add domain here
    },
  })
  `;
  await sandbox.filesystem.writeFile('app/vite.config.js', viteConfig);

Run npm install using the runCommand method

  // Install dependencies
  await sandbox.runCommand('npm install', {
    cwd: 'app',
  })

Start local dev server in the background with runCommand

  // Start dev server
  sandbox.runCommand('npm run dev', {
    cwd: 'app',
  });

Use the getUrl method to get a preview URL

  // Get preview URL
  const url = await sandbox.getUrl({ port: 5173 });
  console.log('previewUrl:', url)

Unlike some providers, Freestyle doesn’t hand you a default preview subdomain automatically — routing a port to a public URL means verifying a domain and pointing its DNS at Freestyle first. Once you’ve mapped one, add it to the allowedHosts array above.

Return the preview url along with the sandboxId

  return NextResponse.json({
    sandboxId: sandbox.sandboxId,
    url,
  });

Finished route.ts file

Your /app/api/sandbox/route.ts file should look like this now:

import { NextResponse } from 'next/server';
import { freestyle } from '@computesdk/freestyle';

const compute = freestyle({
  apiKey: process.env.FREESTYLE_API_KEY,
});

export async function POST() {

  const sandbox = await compute.sandbox.create();

  // Create basic Vite React app
  await sandbox.runCommand('npm create vite@5 app -- --template react');

  // Custom vite.config.js to allow access to sandbox at port 5173
  const viteConfig = `import { defineConfig } from 'vite'
  import react from '@vitejs/plugin-react'

  export default defineConfig({
    plugins: [react()],
    server: {
      host: '0.0.0.0',
      port: 5173,
      strictPort: true,
      hmr: false,
      allowedHosts: ['localhost', '127.0.0.1'] // add domain here
    },
  })
  `;
  await sandbox.filesystem.writeFile('app/vite.config.js', viteConfig);

  // Install dependencies
  await sandbox.runCommand('npm install', {
    cwd: 'app',
  })

  // Start dev server
  sandbox.runCommand('npm run dev', {
    cwd: 'app',
  });

  // Get preview URL
  const url = await sandbox.getUrl({ port: 5173 });
  console.log('previewUrl:', url)

  return NextResponse.json({
    sandboxId: sandbox.sandboxId,
    url,
  });
}

Testing Vite app inside sandbox

Now, after you click the “Create Freestyle Sandbox” button on your localhost homepage you should:

See a new sandbox created in your Freestyle dashboard.
See a preview URL logged to your terminal output.
Finally, if you visit that URL you should see the boilerplate Vite React app running in your Freestyle sandbox!

screenshot of Vite app running in Freestyle sandbox via ComputeSDK

Congrats! You’ve successfully created your first sandbox application

You have done the following:

created a Freestyle sandbox with ComputeSDK
used our runCommand, writeFile, and getUrl methods (these work with any provider whose sandbox supports them)
ran a Vite app inside the sandbox
accessed the app running within the sandbox through its preview URL

ComputeSDK makes it easy to standardize this process across providers.
So now that you’ve written this code for Freestyle, you can easily adjust this code to run in any sandbox provider.

Happy Sandboxing!

Want to get sandboxes running in your application?
Want to be added as a provider?
Reach out to us at [email protected]