<div id="readability-page-1" class="page"><div>OpenAI Codex turns natural-language instructions into code edits and files. Run it inside an E2B Sandbox and you get an isolated, long-running environment where the agent can safely create files, install tools, and execute without interactive prompts.
<h2 id="what-well-build">What we’ll build</h2>
<ul>
<li>Spin up an E2B sandbox from the prebuilt openai-codex template.</li>
<li>Inject your <a href="https://platform.openai.com/api-keys" target="_blank" rel="noopener noreferrer" data-external="true">OpenAI API key</a> into the sandbox.</li>
<li>Run a Codex prompt that creates a Hello World file.</li>
<li>Print the output and shut the sandbox down.</li>
</ul>
<h4 id="see-full-example-in-the-e2b-cookbook">See <a href="https://github.com/e2b-dev/e2b-cookbook/tree/main/examples/openai-codex-in-sandbox-js" target="_blank" rel="noopener noreferrer" data-external="true">full example</a> in the E2B Cookbook.</h4>
<h2 id="components-well-use">Components we’ll use</h2>
<ul>
<li>E2B JS SDK – creates and controls the sandbox.</li>
<li>Prebuilt template: openai-codex – Codex CLI is preinstalled.</li>
<li><code>dotenv</code> – loads <a href="https://console.e2b.dev/?tab=keys" target="_blank" rel="noopener noreferrer" data-external="true"><code>E2B_API_KEY</code></a> from <code>.env</code>.</li>
</ul>
<h2 id="prerequisites">Prerequisites</h2>

<h2 id="outline">Outline</h2>
<ol>
<li>Create the project</li>
<li>Add the files (package.json, src/index.ts)</li>
<li>Set <code>E2B_API_KEY</code> in <code>.env</code></li>
<li>Install and run</li>
</ol>
<h2 id="1-create-the-project">1) Create the project</h2>
<figure><div><pre tabindex="0"><code>mkdir openai-codex-in-sandbox-js
cd openai-codex-in-sandbox-js
mkdir -p src</code></pre></div></figure>
Create and commit .gitignore before .env so secrets never enter git history.
Target structure:
<figure><div><pre tabindex="0"><code>openai-codex-in-sandbox-js/
├─ src/
│ └─ index.ts
├─ package.json
├─ .gitignore
└─ .env</code></pre></div></figure>
<h2 id="2-files-to-add">2) Files to add</h2>
<h3 id="file-packagejson">File: <code>package.json</code></h3>
<figure><div><pre tabindex="0"><code>{
 "name": "openai-codex-in-sandbox",
 "version": "1.0.0",
 "main": "index.js",
 "type": "module",
 "scripts": {
 "start": "tsx src/index.ts"
 },
 "keywords": [],
 "author": "",
 "license": "ISC",
 "description": "",
 "dependencies": {
 "dotenv": "^16.5.0",
 "e2b": "^1.4.0",
 "tsx": "^4.19.4"
 }
}</code></pre></div></figure>
<h3 id="file-gitignore">File: .<code>gitignore</code></h3>
<figure><div><pre tabindex="0"><code>.env
node_modules/</code></pre></div></figure>
<h3 id="file-env">File: .<code>env</code></h3>
<figure><div><pre tabindex="0"><code>E2B_API_KEY="YOUR_E2B_API_KEY"</code></pre></div></figure>
<h3 id="file-srcindexts">File: <code>src/index.ts</code></h3>
This script loads .env (so the SDK sees E2B_API_KEY), creates the sandbox from the openai-codex template while injecting your OpenAI key, runs a Codex exec prompt that generates index.html, prints the result, and then shuts the sandbox down.
Load configuration and SDK:
<figure><div><pre tabindex="0"><code>import { Sandbox } from 'e2b'
import dotenv from 'dotenv'

dotenv.config()</code></pre></div></figure>
Create the sandbox (OpenAI key passed inline) and log its ID:
<figure><div><pre tabindex="0"><code>const templateName = 'openai-codex'
const sbx = await Sandbox.create(templateName, {
 envs: {
 OPENAI_API_KEY: '&lt;your api key&gt;',
 },
})

console.log('Sandbox created', sbx.sandboxId)</code></pre></div></figure>
Run a Codex prompt that creates a file (no per-command timeout):
<figure><div><pre tabindex="0"><code>// Print help for Codex
// const result = await sbx.commands.run('codex --help')
// console.log(result.stdout)

// Run a prompt with Codex
const result = await sbx.commands.run(
 `codex exec --skip-git-repo-check --dangerously-bypass-approvals-and-sandbox "Create a hello world index.html"`,
 { timeoutMs: 0 }
)

console.log(result.stdout)</code></pre></div></figure>
Clean up:
<figure><div><pre tabindex="0"><code>sbx.kill()</code></pre></div></figure>
<h2 id="3-install-run">3) Install &amp; run</h2>
<figure><div><pre tabindex="0"><code>npm install
npm run start</code></pre></div></figure>
Expected: console output from Codex. The generated index.html lives inside the sandbox filesystem.
<h4 id="see-full-example-in-the-e2b-cookbook-1">See <a href="https://github.com/e2b-dev/e2b-cookbook/tree/main/examples/openai-codex-in-sandbox-js" target="_blank" rel="noopener noreferrer" data-external="true">full example</a> in the E2B Cookbook.</h4></div></div>

E2B Blog & Customer Stories

Vaclav Mlejnsky

Run OpenAI Codex in an E2B Sandbox from JavaScript: an isolated, long-running environment where the agent safely creates files, installs tools, and runs code.

JavaScript Guide: Run OpenAI Codex in an E2B Sandbox

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