> In the past 3 weeks I ported Playwright to run completely inside a Chrome extension without Chrome DevTools Protocol (CDP) using purely DOM APIs and Chrome extension APIs, I ported a TypeScript port of Browser Use to run in a Chrome extension side panel using my port of Playwright, in 2 days I ported Selenium ChromeDriver to run inside a Chrome Extension using chrome.debugger APIs which I call ChromeExtensionDriver, and today I'm porting Stagehand to also run in a Chrome extension using the Playwright port. This is following using VSCode's core libraries in a Chrome extension and having them drive a Chrome extension instead of an electron app.
The most difficult part is managing the lifecycle of Windows, Pages, and Frames and handling race conditions, in the case of automating a user's browser, where, for example, the user switches to another tab or closes the tab.
We need the agent to be able to drive 1password, Privacy.com, etc. to request per-task credentials, change adblock settings, get 2fa codes, and more.
The holy grail really is CDP + control over browser launch flags + an extension bridge to get to the more ergonomic `chrome.*` APIs. We're also working on a custom Chromium fork.
1. Get all the things you want.
2. Can create as many 'browser context' personas as you want
3. Use the Electron app renderer for UI to manage profiles, proxies for each profile, automate making gmail accounts for each profile, ect.
4. Forgot, it is very nice using the `--load-extension=/path/to/extension` flag to ship chrome extension files inside the Electron app bundle so that the launched browser will have a cool copilot side panel.
> Extensions are ok but they have limitations too, for example you cannot use extensions to automate other extensions.
5. If you know the extension ids it is easy to set up communication between the two. I already drive a Chrome extension using VSCode's core libraries and it would be a week or two of work to implement a light port of the VSCode host extension API but for a Chrome extension. Nonetheless, I'd rather have an Electron app to manage extensions the same way a VSCode does.
1. There are 3,500,000,000 instances of Chrome desktop being used. [0]
2. A Chrome Extension can be installed with a click from the Chrome Web Store.
3. It is closer to the metal so runs extremely fast.
4. Can run completely contained on the users machine
5. It's just one user automating their web based workflows making it harder for bot protections to stop and with a human-in-the-loop any hang ups and snags can be solved by the human
6. Chrome extensions now have a side panel that is stationary in the window during navigation and tab switching. It is exactly like using the Cursor or VSCode side panel copilots
Some limitations:
1. Can't automate ChatGPT console because they check for user agent events by testing if the `isTrusted` property on event objects is true. (The bypass is using Chrome.debugger and the ChromeExtensionDriver I created.)
2. Can't take full page screen captions however it is possible to very quickly take visible scree captions of the viewport. Currently I scroll and stitch the images together if a full page screen is required. There are other APIs which allow this in a Chrome Extension and can capture video and audio but they require the user to click on some button so it isn't useful for computer vision automation. (The bypass is once again using the Chrome.debugger and ChromeExtensionDriver I created.)
3. Chrome DevTool Protocol allows intercepting and rewriting scripts and web pages before they are evaluated. With manifest v2 this was possible but they removed this ability in manifest v3 which we still hear about today with the adblock extensions.
I feel like with the limitations having a popup dialog that directs the user to do an action will work as long as it automates 98% of the user's workflows. Moreover, a lot of this automation should require explicit user acknowledgments before preceding.
Personally, I have a browser extension running in my user/personal browser instance that my agent use (with rate-limits) in order to avoid all the captchas and blocks basically. Everything else I've tried ultimately ends up getting blocked. But then I'm also doing some heavy caching so most agent "browse" calls end up not even reaching out to the internet as it's finding and using stuff already stored locally.
Microsoft pulled out the lifecycle management code from Puppeteer and put it into Playwright with Google's copyright still at the top of the several files. They both use CDP. I'm using the Chrome extension analogue for every CDP message and listener. I need a couple days to remove all the code from the Page, Frame, FrameManager, and Browser classes and methodically make a state machine with it to track lifecycle and race conditions. It is a huge task and I don't want to share it without accomplishing that.
For example, there is a system that listens for all navigation requests in a Page's / Tab's Frames in Playwright. Embedded frames can navigate to urls which the parent Frame is still loading such as advertising resources, all that needs to be tracked.
There are a lot of companies that are talking about building solutions using CDP without Playwright and I'm curious how well they are going to handle the lifecycle management. Maybe if they don't intercept requests and responses it is very straight forward and simple.
One idea I have is just evaluate '1+1' in the frame's content script in a loop with a backoff strategy and if it returns 2 then continue with code execution or if it times out fail instead of tracking hundreds of navigations with with 30 different embedded frames in a page like CNN. I'm still tinkering. Stagehand calls Locator.evaluate() which is what I'm building because I haven't implemented it yet.
From day one with BrowserBox, we have been using CDP, unadulterated by any higher abstractions. Despite the apparent risk that terrifying changes in the tip-of-tree protocol would lead to disastrous code migrations, none of that ever occurred. The most rewritten code in the application is consistently user interface and core features.
Over the nearly 8 years of BrowserBox’s existence, CDP-related changes due to domain and method deprecations, or subtle changes in parameters or behavior, have been only a very minor maintenance burden. A similar parallel could probably be drawn by examining the Chrome DevTools front-end, another gold-standard CDP-based application, and even digging into its commit history to see how often changes regarding CDP were actually due to protocol-breaking changes.
That was my sense when I began this project: that the protocol is not going to change that much, and we can handle it. My other reason for not choosing Puppeteer or Playwright was that I was dissatisfied with the abstractions they imposed atop CDP, and I found them insufficiently expressive or flexible for the actual demanding use cases of virtualizing a browser in all its aspects — including multiple tabs, managing and bookkeeping all of that state required to do that.
The CDP protocol is still the gold standard for browser instrumentation. It would be nice if Firefox had not deprecated support, and it would be even nicer if WebDriver BiDi was a sufficient and adequate replacement for CDP, which for now it is not. The behavior, logic, and abstractions of CDP are well thought out and highly appropriate for its problem domain. It’s like separating a browser’s engine from its user interface, which is one of the core things BrowserBox accomplishes.
Working with CDP is apparently “difficult,” but that’s just another myth. It’s incredibly easy to write a hundred-or-so-line promise-resolving logic library to ensure you get responses. I’ve done this, and it works. I have used CDP alone in two major, thousands-of-stars, thousands-of-users, significant browser-related projects (the other is DiskerNet), and I have never regretted that choice, nor ever wished that I had switched to Puppeteer or Playwright.
That said, I think the sweet spot for Puppeteer and Playwright is quickly putting together not-overly-complex automation tasks, or other specific browser-instrumentation-related tasks with a fairly narrow scope. The main reason I used CDP was because I wanted the power of access to the full protocol, and I knew that would be the best choice — and it was.
So if your browser-related project is going to require deep integration with the browser and access to everything that’s exposed, don’t even think twice about using CDP. Just use it. The only caveat I would make to that is: keep an eye on whether WebDriver BiDi capabilities become sufficient for your use case, and seriously consider a WebDriver BiDi implementation, because that gives you a broader swath of browsers you’ll be able to use as the engine.
[1] https://chromedevtools.github.io/devtools-protocol/
[2] https://github.com/ChromeDevTools/devtools-frontend
Now that I got my snarky remark out of the way:
Puppeteer uses CDP under the hood. Just use Puppeteer.
I don't know how well it would work for that use-case, but I've used it before, for example, to write a web-crawler that could handle client-side rendering.
We're currently using Cypress for some automated testing on a recent project and its extremely brittle. Considering moving to playwright or puppeteer but not sure if that will fix the brittleness.
It is also just really easy to write a performant test suite with Playwright, it is easy to parallelize, which is terrible in Cypress, almost intentionally so to sell their cloud products, which you do not need. The way Playwright works just feels more intuitive and stable to me.
Playwright's "trace" viewer is also fantastic providing periodic snapshots and performance debugging.
There was a ton of this stuff before Chrome or WebKit even existed! Back in my day, we used Selenium and hated it. (I was lucky enough to start after Mercury...)
I still deeply appreciate these tools, even though I also find them a bit frustrating.
We had a complex user registration workflow that supported multiple nationalities and languages in a international bank website.
I setup selenium tests to detect breakages because it was almost humanly impossible to retest all workflows after every sprint.
It brought back sanity to the team and QA folks.
Tools that came after certainly benefitted from selenium lessons.
https://github.com/browser-use/website/blob/main/posts/playw...
Guess how IE became what it was before the lawsuit, it was the cool browser when all nice developer features came first.
Dynamic HTML, HTML Applications, CSS shaders (backed by DirectX), VS debugging integration (via Frontpage)...
Apparently a lesson gone after one generation.
There are no extra checks needed it's by a significant margin the most reliable method to see current state.
I run snapshot at 10-20fps though plus the same for parallel image capture.
I've been wondering if I should release just this part of my system open source seems like I'm not alone in how complex this all is.
I could launch yet another automation framework!
Karma like approaches are where I’m at (execute in the browser)
Why? I would think any cross-process communication through the CDP websocket would have imperceptible overhead compared to what already takes long in the browser: a ton of HTTP I/O
What is Karma? What are you executing in the browser?
Cdp does add a good chunk of latency. Depends on what your threshold is.
An image grab is around 60ms and a snapshot can range from 40ms -> 500ms
The latency is pure data movement. It's like the difference of using ram vs ssd vs data from the internet.
This post is like saying Grafana and not mentioning Nagios
Selenium offered headless mode and integrated with 3rd party providers like BrowserStack, which ran acceptance tests in parallel in the cloud. It seems like what browser-use.com is doing is a modern day version with many more features & adaptability.
it's a bummer, but also a market reality... the best way to get more devs to care about non-chrome browsers is to get more people to use non-chrome browsers. easier said than done, though.
Good luck guys!
I build something like an automation system pure cdp to shave ms off. But I'm a real time user interaction system plus automation not pure ai automation.
Doesn't make much sense to shave ms when an LLM call is hundreds of ms ans that's the only "user"
That isn't how you launch a product.
Personally have not found their team to be the easiest to work with on Github. I would've loved to use puppeteer instead, their team is quite reasonable but they abandoned their python bindings and we want to stay in python.
By the very nature of how Playwright is built we can't contribute to it - it runs inside a JS subprocess and does not expose a bunch of CDP apis that we NEED (for example to make cross origin iframes work).
