3c0c75be10
Any object we return from Zig to V8 becomes a v8::Global that we track in our `ctx.identity_map`. V8 will not free such objects. On the flip side, on its own, our Zig code never knows if the underlying v8::Object of a global can still be used from JS. Imagine an XHR request where we fire the last readyStateChange event..we might think we no longer need that XHR instance, but nothing stops the JavaScript code from holding a reference to it and calling a property on it, e.g. `xhr.status`. What we can do is tell v8 that we're done with the global and register a callback. We make our reference to the global weak. When v8 determines that this object cannot be reached from JavaScript, it _may_ call our registered callback. We can then clean things up on our side and free the global (we actually _have_ to free the global). v8 makes no guarantee that our callback will ever be called, so we need to track these finalizable objects and free them ourselves on context shutdown. Furthermore there appears to be some possible timing issues, especially during context shutdown, so we need to be defensive and make sure we don't double-free (we can use the existing identity_map for this). An type like XMLHttpRequest can be re-used. After a request succeeds or fails, it can be re-opened and a new request sent. So we also need a way to revert a "weak" reference back into a "strong" reference. These are simple v8 calls on the v8::Global, but it highlights how sensitive all this is. We need to mark it as weak when we're 100% sure we're done with it, and we need to switch it to strong under any circumstances where we might need it again on our side. Finally, none of this makes sense if there isn't something to free. Of course, the finalizer lets us release the v8::Global, and we can free the memory for the object itself (i.e. the `*XMLHttpRequest`). This PR also adds an ArenaPool. This allows the XMLHTTPRequest to be self-contained and not need the `page.arena`. On init, the `XMLHTTPRequest` acquires an arena from the pool. On finalization it releases it back to the pool. So we now have: - page.call_arena: short, guaranteed for 1 v8 -> zig -> v8 flow - page.arena long: lives for the duration of the entire page - page.arena_pool: ideally lives for as long as needed by its instance (but no guarantees from v8 about this, or the script might leak a lot of global, so worst case, same as page.arena)
Lightpanda Browser
Lightpanda is the open-source browser made for headless usage:
- Javascript execution
- Support of Web APIs (partial, WIP)
- Compatible with Playwright1 , Puppeteer, chromedp through CDP
Fast web automation for AI agents, LLM training, scraping and testing:
- Ultra-low memory footprint (9x less than Chrome)
- Exceptionally fast execution (11x faster than Chrome)
- Instant startup
Puppeteer requesting 100 pages from a local website on a AWS EC2 m5.large instance. See benchmark details.
Quick start
Install
Install from the nightly builds
You can download the last binary from the nightly builds for Linux x86_64 and MacOS aarch64.
For Linux
curl -L -o lightpanda https://github.com/lightpanda-io/browser/releases/download/nightly/lightpanda-x86_64-linux && \
chmod a+x ./lightpanda
For MacOS
curl -L -o lightpanda https://github.com/lightpanda-io/browser/releases/download/nightly/lightpanda-aarch64-macos && \
chmod a+x ./lightpanda
For Windows + WSL2
The Lightpanda browser is compatible to run on windows inside WSL. Follow the Linux instruction for installation from a WSL terminal. It is recommended to install clients like Puppeteer on the Windows host.
Install from Docker
Lightpanda provides official Docker
images for both Linux amd64 and
arm64 architectures.
The following command fetches the Docker image and starts a new container exposing Lightpanda's CDP server on port 9222.
docker run -d --name lightpanda -p 9222:9222 lightpanda/browser:nightly
Dump a URL
./lightpanda fetch --dump https://lightpanda.io
info(browser): GET https://lightpanda.io/ http.Status.ok
info(browser): fetch script https://api.website.lightpanda.io/js/script.js: http.Status.ok
info(browser): eval remote https://api.website.lightpanda.io/js/script.js: TypeError: Cannot read properties of undefined (reading 'pushState')
<!DOCTYPE html>
Start a CDP server
./lightpanda serve --host 127.0.0.1 --port 9222
info(websocket): starting blocking worker to listen on 127.0.0.1:9222
info(server): accepting new conn...
Once the CDP server started, you can run a Puppeteer script by configuring the
browserWSEndpoint.
'use strict'
import puppeteer from 'puppeteer-core';
// use browserWSEndpoint to pass the Lightpanda's CDP server address.
const browser = await puppeteer.connect({
browserWSEndpoint: "ws://127.0.0.1:9222",
});
// The rest of your script remains the same.
const context = await browser.createBrowserContext();
const page = await context.newPage();
// Dump all the links from the page.
await page.goto('https://wikipedia.com/');
const links = await page.evaluate(() => {
return Array.from(document.querySelectorAll('a')).map(row => {
return row.getAttribute('href');
});
});
console.log(links);
await page.close();
await context.close();
await browser.disconnect();
Telemetry
By default, Lightpanda collects and sends usage telemetry. This can be disabled by setting an environment variable LIGHTPANDA_DISABLE_TELEMETRY=true. You can read Lightpanda's privacy policy at: https://lightpanda.io/privacy-policy.
Status
Lightpanda is in Beta and currently a work in progress. Stability and coverage are improving and many websites now work. You may still encounter errors or crashes. Please open an issue with specifics if so.
Here are the key features we have implemented:
- HTTP loader (Libcurl)
- HTML parser (html5ever)
- DOM tree
- Javascript support (v8)
- DOM APIs
- Ajax
- XHR API
- Fetch API
- DOM dump
- CDP/websockets server
- Click
- Input form
- Cookies
- Custom HTTP headers
- Proxy support
- Network interception
NOTE: There are hundreds of Web APIs. Developing a browser (even just for headless mode) is a huge task. Coverage will increase over time.
You can also follow the progress of our Javascript support in our dedicated zig-js-runtime project.
Build from sources
Prerequisites
Lightpanda is written with Zig 0.15.2. You have to
install it with the right version in order to build the project.
Lightpanda also depends on zig-js-runtime (with v8), Libcurl and html5ever.
To be able to build the v8 engine for zig-js-runtime, you have to install some libs:
For Debian/Ubuntu based Linux:
sudo apt install xz-utils ca-certificates \
clang make curl git
You also need to install Rust.
For systems with Nix, you can use the devShell:
nix develop
For MacOS, you need cmake and Rust.
brew install cmake
Install Git submodules
The project uses git submodules for dependencies.
To init or update the submodules in the vendor/ directory:
make install-submodule
This is an alias for git submodule init && git submodule update.
Build and run
You an build the entire browser with make build or make build-dev for debug
env.
But you can directly use the zig command: zig build run.
Embed v8 snapshot
Lighpanda uses v8 snapshot. By default, it is created on startup but you can embed it by using the following commands:
Generate the snapshot.
zig build snapshot_creator -- src/snapshot.bin
Build using the snapshot binary.
zig build -Dsnapshot_path=../../snapshot.bin
See #1279 for more details.
Test
Unit Tests
You can test Lightpanda by running make test.
End to end tests
To run end to end tests, you need to clone the demo
repository into ../demo dir.
You have to install the demo's node requirements
You also need to install Go > v1.24.
make end2end
Web Platform Tests
Lightpanda is tested against the standardized Web Platform Tests.
The relevant tests cases are committed in a dedicated repository which is fetched by the make install-submodule command.
All the tests cases executed are located in the tests/wpt sub-directory.
For reference, you can easily execute a WPT test case with your browser via wpt.live.
Run WPT test suite
To run all the tests:
make wpt
Or one specific test:
make wpt Node-childNodes.html
Add a new WPT test case
We add new relevant tests cases files when we implemented changes in Lightpanda.
To add a new test, copy the file you want from the WPT
repo into the tests/wpt directory.
⚠️ Please keep the original directory tree structure of tests/wpt.
Contributing
Lightpanda accepts pull requests through GitHub.
You have to sign our CLA during the pull request process otherwise we're not able to accept your contributions.
Why?
Javascript execution is mandatory for the modern web
In the good old days, scraping a webpage was as easy as making an HTTP request, cURL-like. It’s not possible anymore, because Javascript is everywhere, like it or not:
- Ajax, Single Page App, infinite loading, “click to display”, instant search, etc.
- JS web frameworks: React, Vue, Angular & others
Chrome is not the right tool
If we need Javascript, why not use a real web browser? Take a huge desktop application, hack it, and run it on the server. Hundreds or thousands of instances of Chrome if you use it at scale. Are you sure it’s such a good idea?
- Heavy on RAM and CPU, expensive to run
- Hard to package, deploy and maintain at scale
- Bloated, lots of features are not useful in headless usage
Lightpanda is built for performance
If we want both Javascript and performance in a true headless browser, we need to start from scratch. Not another iteration of Chromium, really from a blank page. Crazy right? But that’s what we did:
- Not based on Chromium, Blink or WebKit
- Low-level system programming language (Zig) with optimisations in mind
- Opinionated: without graphical rendering
-
Playwright support disclaimer: Due to the nature of Playwright, a script that works with the current version of the browser may not function correctly with a future version. Playwright uses an intermediate JavaScript layer that selects an execution strategy based on the browser's available features. If Lightpanda adds a new Web API, Playwright may choose to execute different code for the same script. This new code path could attempt to use features that are not yet implemented. Lightpanda makes an effort to add compatibility tests, but we can't cover all scenarios. If you encounter an issue, please create a GitHub issue and include the last known working version of the script. ↩︎