Playwright

Connect Playwright to a Kernel cloud browser over CDP

Playwright is a browser automation library from Microsoft. Kernel browsers speak the Chrome DevTools Protocol (CDP), so you can point an existing Playwright script at a cloud browser by swapping your launch call for a connectOverCDP to the session’s cdp_ws_url — no other code changes.

If you don’t need a local Playwright install and want your code to run co-located with the browser, use Playwright Execution instead. It runs the same Playwright API inside the browser’s VM and returns values back to your agent. This page covers connecting a Playwright client you run yourself.

Install

npm install playwright @onkernel/sdk

pip install playwright kernel

Create a browser and connect

Create a Kernel browser, then connect Playwright to its cdp_ws_url. Kernel opens a context and page for you — grab them from the connected browser rather than calling newContext.

Typescript/Javascript

import { chromium } from 'playwright';
import Kernel from '@onkernel/sdk';

const kernel = new Kernel();

const kernelBrowser = await kernel.browsers.create();
console.log('Live view:', kernelBrowser.browser_live_view_url);

const browser = await chromium.connectOverCDP(kernelBrowser.cdp_ws_url);
const context = browser.contexts()[0];
const page = context.pages()[0];

await page.goto('https://onkernel.com');
console.log(await page.title());

await browser.close();
await kernel.browsers.deleteByID(kernelBrowser.session_id);

import asyncio
from kernel import Kernel
from playwright.async_api import async_playwright

kernel = Kernel()

async def main():
    kernel_browser = kernel.browsers.create()
    print("Live view:", kernel_browser.browser_live_view_url)

    async with async_playwright() as playwright:
        browser = await playwright.chromium.connect_over_cdp(kernel_browser.cdp_ws_url)
        context = browser.contexts[0]
        page = context.pages[0]

        await page.goto("https://onkernel.com")
        print(await page.title())

        await browser.close()

    kernel.browsers.delete_by_id(kernel_browser.session_id)

asyncio.run(main())

Configure the viewport

Set the viewport when you create the browser, not through Playwright. Playwright’s setViewportSize is a no-op over a CDP connection — the window size is fixed at browser creation. See Viewports for supported dimensions and refresh rates.

Typescript/Javascript

const kernelBrowser = await kernel.browsers.create({
  viewport: { width: 1280, height: 720 },
});

kernel_browser = kernel.browsers.create(
    viewport={"width": 1280, "height": 720},
)

Stealth mode

Create the browser with stealth: true to harden it against bot detection. The connection is unchanged — you still connect Playwright to cdp_ws_url.

Typescript/Javascript

const kernelBrowser = await kernel.browsers.create({ stealth: true });

kernel_browser = kernel.browsers.create(stealth=True)

See stealth mode for what it changes. For the strongest anti-detection posture, prefer computer controls or Playwright Execution — a direct CDP connection carries a fingerprint that co-located control avoids.

Why run Playwright on Kernel

• No local browser management. No Chromium download or version pinning on your machine — the browser runs in Kernel’s cloud.
• Persistent state. Keep cookies and login state across runs with Profiles.
• Scale out. Launch many sessions in parallel instead of contending for one local browser.
• Debuggable. Watch any session in real time with live view.
• No code rewrite. Existing Playwright scripts work as-is once you swap the launch for connectOverCDP.

Next steps

• Playwright Execution — run Playwright inside the browser VM with no local install
• Live view — watch and debug your sessions
• Stealth mode — avoid bot detection
• Terminating sessions — clean up browsers when you’re done