DevTools protocol

For every running session WebSummoner proxies the Chrome DevTools protocol to the browser container. Point any CDP client at:

<ws-or-http>://websummoner.example.com:4444/devtools/<session-id>/<method>

Note

CDP is a Chromium protocol, so this works for the Chromium-based images — Chrome, Edge, Opera, Yandex and Brave. Firefox and WebKit have no CDP endpoint, and WebSummoner deliberately does not advertise one for them: a client that saw se:cdp there would fail on its first WebSocket handshake.

Caution

CDP is on its way out. Firefox disabled it by default in Firefox 129, Selenium removed its Firefox CDP support in 4.29, and the cross-browser replacement is WebDriver BiDi. WebSummoner does not proxy BiDi yet — if your tests need bidirectional features on Firefox or WebKit, that is not available through the grid today. Prefer BiDi in new test code where your client supports it directly.

Supported methods

Method	Protocol	Meaning
/browser	WebSocket	Browser-level DevTools websocket
/	WebSocket	Alias for /browser
/page	WebSocket	Current page (target) websocket — ideal when a single tab is open
/page/<target-id>	WebSocket	Websocket for a specific tab
/json/protocol	HTTP	Supported protocol methods as JSON (used by some client libraries)

For example, the current-page websocket is:

ws://websummoner.example.com:4444/devtools/<session-id>/page

Example: Puppeteer over a WebdriverIO session

Because the Selenium session and the CDP connection share the same browser, you can mix high-level Selenium actions with Puppeteer’s low-level access:

const { remote } = require('webdriverio');
const puppeteer = require('puppeteer-core');
const host = 'websummoner.example.com';

(async () => {
    const browser = await remote({
        hostname: host,
        capabilities: {
            browserName: 'chrome',
            browserVersion: '152.0',
        },
    });

    const devtools = await puppeteer.connect({
        browserWSEndpoint: `ws://${host}:4444/devtools/${browser.sessionId}`,
    });

    const page = await devtools.newPage();
    await page.goto('https://example.com');
    await page.screenshot({ path: 'screenshot.png' });
    console.log(await page.title());

    await devtools.close();
    await browser.deleteSession();
})().catch((e) => console.error(e));