Just last week, together with BrowserStack, we announced WebDriver BiDi becoming production-ready in BrowserStack. This week the summer of WebDriver BiDi continues with Firefox 129 and Puppeteer 23 each getting production-ready support for WebDriver BiDi!
Mozilla has been a strong collaborator on WebDriver BiDi for over four years now, initially helping to shape the new standard and then gradually implementing it in Firefox, neatly documenting their progress with the Firefox WebDriver Newsletter.
With WebDriver BiDi now production-ready in Firefox, Puppeteer, from version 23, offers stable support for Firefox through WebDriver BiDi. This lets you automate Firefox with the same concise API as Chrome. Puppeteer's support for Chrome DevTools Protocol (CDP) remains unchanged.
Firefox, CDP, and Puppeteer
Puppeteer is a reliable tool for developers to automate Chromium-based browsers using the Chrome DevTools Protocol, also known as CDP. In 2019 Puppeteer got experimental support for Firefox.
To make this work, Mozilla implemented and maintained a subset of CDP in Firefox. This solution let Firefox be automated with the Puppeteer API, but it had caveats:
- As the name suggests, the CDP is used by Chrome's DevTools and needs to change with DevTools requirements.
- The CDP is not standardized in a shared, public specification and maintaining it in Firefox required steady communication and effort.
- Since Firefox only implemented a subset of CDP, Puppeteer could never guarantee its full API to work with Firefox, creating confusion for users.
While we're glad to have maintained this support together with Mozilla for the last few years, we always knew it wasn't a permanent solution. Building on this partnership, and including other major browser and tooling vendors, together we created WebDriver BiDi.
Teamwork makes the dream work
The Firefox team has been eagerly working to implement WebDriver BiDi in Firefox. At the same time the Puppeteer team has been expanding WebDriver BiDi support across the Puppeteer API. The goal that both teams worked towards was to make every API required for production automation use cases available using WebDriver BiDi in Puppeteer, ensuring support in both Chrome and Firefox.
This lets Puppeteer users select either Firefox or Chrome for their automations,
by specifying the browser configuration key when launching a Puppeteer
instance.
import puppeteer from 'puppeteer';
const firefoxBrowser = await puppeteer.launch({
browser: 'firefox', // WebDriver BiDi is used by default in Firefox.
});
const page = await firefoxBrowser.newPage();
...
await firefoxBrowser.close();
const chromeBrowser = await puppeteer.launch({
browser: 'chrome',
protocol: 'webDriverBiDi', // CDP would be used by default for Chrome.
});
const page = await chromeBrowser.newPage();
...
await chromeBrowser.close();
To learn more about what's new in Firefox 129 and Mozilla's work on WebDriver BiDi see the related Mozilla Hacks blog post.
CDP support in the future
The preceding code snippet shows that to automate Chrome using
WebDriver BiDi with Puppeteer you need to explicitly set protocol to
webDriverBiDi. This is because for Chrome, Puppeteer will keep defaulting to
CDP—to not break existing automations, but also to keep supporting automations
specialized to Chrome's features.
CDP support in Firefox is deprecated from Firefox 129 and scheduled to be removed at the end of 2024. If you have existing automations that rely on CDP support in Firefox we strongly recommend migrating to WebDriver BiDi. If that's not possible, reach out to dev-webdriver@mozilla.org with your use case.