> ## Documentation Index
> Fetch the complete documentation index at: https://tbd-6fc993ce-hypeship-docs-ia-restructure.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Steel

> Move a Steel automation to Kernel

Steel and Kernel both hand you a hosted Chromium over CDP, so the connection swap is one line. The differences worth planning for are what happens around the session.

## Concept mapping

| Concept                     | Steel                         | Kernel                                                                                                  |
| --------------------------- | ----------------------------- | ------------------------------------------------------------------------------------------------------- |
| Create a session            | `client.sessions.create()`    | `kernel.browsers.create()`                                                                              |
| CDP endpoint                | Session `websocketUrl`        | `browser.cdp_ws_url`                                                                                    |
| Release a session           | `client.sessions.release(id)` | `kernel.browsers.deleteByID(session_id)`, or let [`timeout_seconds`](/browsers/termination) expire      |
| Live session viewer         | Session viewer URL            | `browser.browser_live_view_url`, returned on create                                                     |
| Persisted state             | Session context / credentials | [Profiles](/auth/profiles), populated and maintained by [managed auth](/auth/overview)                  |
| Stealth                     | Stealth session flag          | Anti-detection by default; `stealth: true` adds the managed proxy and CAPTCHA solver                    |
| CAPTCHA solving             | Session solver option         | Included with [stealth mode](/browsers/bot-detection/stealth)                                           |
| Proxies                     | Session proxy, billed per GB  | [Proxies](/proxies/overview), unmetered on Kernel-provided types                                        |
| Files                       | Session files API             | [File I/O](/browsers/file-io)                                                                           |
| Extensions                  | Session extensions            | [Extensions](/browsers/extensions)                                                                      |
| Warm sessions               | —                             | [Browser pools](/browsers/pools)                                                                        |
| Run code beside the browser | —                             | [Playwright execution](/browsers/playwright-execution), [App Platform](/apps/overview)                  |
| Self-hosting                | Open-source Steel server      | Not applicable — see [migrating from self-hosted](/migrations/self-hosted) if that's what you run today |

## The connection change

```typescript theme={null}
import Kernel from '@onkernel/sdk';
import { chromium } from 'playwright-core';

const kernel = new Kernel();
const kernelBrowser = await kernel.browsers.create({ stealth: true, timeout_seconds: 600 });

const browser = await chromium.connectOverCDP(kernelBrowser.cdp_ws_url);
const page = browser.contexts()[0].pages()[0];
await page.goto('https://example.com');
await browser.close();

await kernel.browsers.deleteByID(kernelBrowser.session_id);
```

## What to change next

* **Stop connecting over CDP for the hot path.** [Playwright execution](/browsers/playwright-execution) runs your code inside the browser's VM and returns values, with no connection to manage and no CDP fingerprint on the wire. See [how you drive the browser](/introduction/driving-the-browser).
* **Replace credential handling with [managed auth](/auth/overview).** Kernel performs the login, keeps the session warm with health checks, and writes the result into a [profile](/auth/profiles) your browsers attach.
* **Use a [pool](/browsers/pools) for repeated work.** Pool acquisition skips both browser creation and the per-plan [create rate](/browsers/concurrency-and-limits#create-rate).

<Note>
  If you were self-hosting Steel to control cost or data residency, read [zero data retention](/info/zero-data-retention) and [security practices](/security) before you plan the move.
</Note>