Persistence allows you to reuse a browser’s state, including cookies, session auth, cache, and any other state that lives on a browser. This can be used to minimize CAPTCHAs and login flows.

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Reusing a browser

To reuse a browser over multiple invocations, specify persist settings in the browsers.create() method:

const playwrightScript = async (runtimeContext, payload) => {
	const kernelBrowser = await Kernel.browsers.create({
		invocation_id: runtimeContext.invocation_id,
		persistence: { id: "unique-browser-id-for-persistence" },
	});
	const browser = await chromium.connectOverCDP(kernelBrowser.cdp_ws_url);
	// ...
};

During runtime, Kernel will search for a browser with the specified id:

  • If a browser with the specified persistence id is found, the existing browser will be provided to your app.
  • If a browser with the specified persistence id is not found, a new browser instance will be created and assigned the specified persistence id for future reuse.
  • Reusing an existing browser restores its exactly state and stealth configurations (stealth configs cannot be changed for an existing browser).

The browser’s persistence id can be any string. You can set it to an identifier in your system to match it to a user, environment, website, or something else.

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Notes about persistence

  • If you don’t mark the browser for persistence when calling browsers.create(), the browser will be destroyed after the invocation completes.
  • Browsers can only maintain one connection at a time, so the invocation will fail if there is already a connection in progress.
  • When reusing a browser, your app’s logic should account for scenarios where cookies are present (for example, skip login details if already authenticated) as well as when they’re not (in case the cookies have expired).
  • Most websites’ authentication schemes set TTLs. Kernel’s browser persistence helps you reuse the browser’s cookies, but they’re only valid as long as the cookies’ TTL.

See the CLI reference for full details.