Changelog

New features

Sandbox REST API

The modbox/sandbox image now exposes a built-in REST API for programmatic interaction without requiring a full browser or terminal session.

Exec endpoint — run any shell command and get stdout, stderr, exit code and duration:

$
POST {sandbox_url}/modbox/api/exec
$
Authorization: Bearer {SANDBOX_API_KEY}
$
$
{
>
  "command": "python3 script.py",
>
  "timeout": 15000,
>
  "cwd": "/workspace"
>
}

Response includes exitCode, stdout, stderr, durationMs, and a truncated flag if output exceeded 512 KB.

Files endpoint — upload, list, download and delete files inside the sandbox:

POST   {sandbox_url}/modbox/api/files/upload      (multipart, max 50 MB)
GET    {sandbox_url}/modbox/api/files
GET    {sandbox_url}/modbox/api/files/download/{filename}
DELETE {sandbox_url}/modbox/api/files/{filename}

All /modbox/api/* routes require Authorization: Bearer {SANDBOX_API_KEY}. Pass SANDBOX_API_KEY as an env_var when provisioning the sandbox.

MCP server endpoints

Every modbox/sandbox instance now exposes two built-in MCP servers accessible directly from the sandbox URL:

Connect any MCP-compatible client (Claude Desktop, VS Code, custom agents) by pointing it at either endpoint — no additional configuration required.

CDP proxy improvements

The Chromium CDP endpoint (/cdp/) now correctly rewrites WebSocket debugger URLs in responses, allowing Playwright and Puppeteer to connect through the proxy without manual URL manipulation.

Use connectOverCDP with the HTTP endpoint:

1
const browser = await chromium.connectOverCDP(
2
  `https://${new URL(sandbox.sandboxUrl).host}/cdp`
3
);

Documentation

• New guide: The modbox/sandbox Image — covers all routes, the exec and files API, CDP setup, VNC access, MCP integration, proxy support, and comparison with modbox/sandbox-lite