Lightpanda Browser

The headless browser built from scratch for AI agents and automation.
Not a Chromium fork. Not a WebKit patch. A new browser, written in Zig.

chromedp requesting 933 real web pages over the network on a AWS EC2 m5.large instance. See benchmark details.

Lightpanda is the open-source browser made for headless usage:

Javascript execution
Support of Web APIs (partial, WIP)
Compatible with Playwright[^1], 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

[^1]: 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.

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 --obey-robots --log-format pretty  --log-level info https://demo-browser.lightpanda.io/campfire-commerce/

INFO  telemetry : telemetry status . . . . . . . . . . . . .  [+0ms]
      disabled = false

INFO  page : navigate . . . . . . . . . . . . . . . . . . . . [+6ms]
      url = https://demo-browser.lightpanda.io/campfire-commerce/
      method = GET
      reason = address_bar
      body = false
      req_id = 1

INFO  browser : executing script . . . . . . . . . . . . . .  [+118ms]
      src = https://demo-browser.lightpanda.io/campfire-commerce/script.js
      kind = javascript
      cacheable = true

INFO  http : request complete . . . . . . . . . . . . . . . . [+140ms]
      source = xhr
      url = https://demo-browser.lightpanda.io/campfire-commerce/json/product.json
      status = 200
      len = 4770

INFO  http : request complete . . . . . . . . . . . . . . . . [+141ms]
      source = fetch
      url = https://demo-browser.lightpanda.io/campfire-commerce/json/reviews.json
      status = 200
      len = 1615
<!DOCTYPE html>

Start a CDP server

./lightpanda serve --obey-robots --log-format pretty  --log-level info --host 127.0.0.1 --port 9222

INFO  telemetry : telemetry status . . . . . . . . . . . . .  [+0ms]
      disabled = false

INFO  app : server running . . . . . . . . . . . . . . . . .  [+0ms]
      address = 127.0.0.1:9222

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://demo-browser.lightpanda.io/amiibo/', {waitUntil: "networkidle0"});

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
Respect robots.txt with option --obey-robots

NOTE: There are hundreds of Web APIs. Developing a browser (even just for headless mode) is a huge task. Coverage will increase over time.

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 v8, Libcurl and html5ever.

To be able to build the v8 engine, you have to install some libs:

For Debian/Ubuntu based Linux:

sudo apt install xz-utils ca-certificates \
    pkg-config libglib2.0-dev \
    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

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.

We use a fork including a custom testharnessreport.js.

For reference, you can easily execute a WPT test case with your browser via wpt.live.

Configure WPT HTTP server

To run the test, you must clone the repository, configure the custom hosts and generate the MANIFEST.json file.

Clone the repository with the fork branch.

git clone -b fork --depth=1 git@github.com:lightpanda-io/wpt.git

Enter into the wpt/ dir.

Install custom domains in your /etc/hosts

./wpt make-hosts-file | sudo tee -a /etc/hosts

Generate MANIFEST.json

./wpt manifest

Use the WPT’s setup guide for details.

Run WPT test suite

An external Go runner is provided by github.com/lightpanda-io/demo/ repository, located into wptrunner/ dir. You need to clone the project first.

First start the WPT’s HTTP server from your wpt/ clone dir.

./wpt serve

Run a Lightpanda browser

zig build run -- --insecure-disable-tls-host-verification

Then you can start the wptrunner from the Demo’s clone dir:

cd wptrunner && go run .

Or one specific test:

cd wptrunner && go run . Node-childNodes.html

wptrunner command accepts --summary and --json options modifying output. Also --concurrency define the concurrency limit.

Running the whole test suite will take a long time. In this case, it’s useful to build in releaseFast mode to make tests faster.

zig build -Doptimize=ReleaseFast run

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