Ladybird — Independent Web Browser Built from Scratch

Introduction

Ladybird is an independent web browser that uses its own rendering engine, LibWeb, and JavaScript engine, LibJS. Born out of the SerenityOS project, it was spun off as a standalone cross-platform browser targeting Linux, macOS, and Windows. Its goal is to offer a genuinely independent alternative to Chromium and Gecko-based browsers.

What Ladybird Does

• Renders web pages using its own LibWeb engine with growing CSS and HTML spec coverage
• Executes JavaScript through LibJS, a custom ECMAScript engine
• Supports modern web standards including CSS Grid, Flexbox, and ES modules
• Handles HTTPS, WebSockets, and modern TLS via its networking stack
• Provides a tabbed browsing UI with developer tools

Architecture Overview

Ladybird is built in C++ (C++23) with a multi-process architecture. Each tab runs in its own process for isolation. The rendering pipeline goes from HTML parsing through the DOM, layout tree construction, and painting via LibGfx. LibJS handles script execution with a bytecode interpreter. LibWeb ties the DOM, CSS, and JS worlds together into a full rendering engine.

Self-Hosting & Configuration

• Build requires CMake 3.25+, Ninja, and a C++23-capable compiler (GCC 13+ or Clang 17+)
• Supported on Linux (primary), macOS, and experimental Windows builds
• No installer packages yet; built from source
• Configuration is minimal; settings are compiled in or set at runtime
• Nightly builds are available for macOS via the project website

Key Features

• Fully independent engine: no Blink, Gecko, or WebKit code
• Multi-process tab isolation for stability and security
• Rapidly growing web compatibility with regular spec compliance improvements
• Lightweight codebase compared to major browser engines
• Active open-source community with welcoming contributor culture

Comparison with Similar Tools

• Chromium — dominant engine but monoculture risk; Ladybird offers genuine diversity
• Firefox (Gecko) — established independent engine; Ladybird is younger but has a clean-slate design
• Safari (WebKit) — Apple-focused; Ladybird targets cross-platform from the start
• Servo — Rust-based experimental engine; Ladybird is C++ and ships a full browser UI
• Pale Moon (Goanna) — forked from older Gecko; Ladybird is entirely new code

FAQ

Q: Is Ladybird ready for daily use? A: Not yet. It is in active development and many websites will not render correctly. It is best used for testing and contributing.

Q: How does Ladybird relate to SerenityOS? A: Ladybird started as the browser component of SerenityOS but was forked into a standalone project in 2024 to focus on cross-platform support.

Q: Does Ladybird support browser extensions? A: Not currently. Extension support is not yet a priority, as the focus is on core engine compatibility.

Q: What platforms does Ladybird run on? A: Linux and macOS are the primary targets. Windows support is experimental and improving.

Sources

• https://github.com/LadybirdBrowser/ladybird
• https://ladybird.org