Build instructions

Complete build instructions for Ladybird browser across all supported platforms

Build prerequisites

Qt6 development packages, nasm, additional build tools, and a C++23 capable compiler are required.

A Rust toolchain is also required for building the JavaScript engine. You can install it via rustup or your system’s package manager.

We currently use gcc-14 and clang-21 in our CI pipeline. If these versions are not available on your system, see Meta/find_compiler.py for the minimum compatible version.

CMake 3.30 or newer must be available in $PATH.

---

Platform-specific dependencies

Debian/Ubuntu

1. Install base dependencies

   sudo apt install autoconf autoconf-archive automake build-essential ccache cmake curl fonts-liberation2 git libdrm-dev libgl1-mesa-dev libtool nasm ninja-build pkg-config python3-venv qt6-base-dev qt6-tools-dev-tools qt6-wayland tar unzip zip
   
2. Install CMake 3.30 or newer

   This repository is Ubuntu-only

   # Add Kitware GPG signing key
   wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | sudo tee /usr/share/keyrings/kitware-archive-keyring.gpg >/dev/null
   
   # Use the key to authorize an entry for apt.kitware.com in apt sources list
   echo "deb [signed-by=/usr/share/keyrings/kitware-archive-keyring.gpg] https://apt.kitware.com/ubuntu/ $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/kitware.list
   
   # Update apt package list and install cmake
   sudo apt update -y && sudo apt install cmake -y
   
3. Install a C++23-capable compiler

   Clang (Recommended)

   Install clang from LLVM’s apt repository:

   # Add LLVM GPG signing key
   sudo wget -O /usr/share/keyrings/llvm-snapshot.gpg.key https://apt.llvm.org/llvm-snapshot.gpg.key
   
   # Use the key to authorize an entry for apt.llvm.org in apt sources list
   echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg.key] https://apt.llvm.org/$(lsb_release -sc)/ llvm-toolchain-$(lsb_release -sc)-21 main" | sudo tee -a /etc/apt/sources.list.d/llvm.list
   
   # Update apt package list and install clang and associated packages
   sudo apt update -y && sudo apt install clang-21 clangd-21 clang-tools-21 clang-format-21 clang-tidy-21 lld-21 -y
   

   GCC (Alternative)

   Install gcc from Ubuntu Toolchain PPA:

   sudo add-apt-repository ppa:ubuntu-toolchain-r/test
   sudo apt update && sudo apt install g++-14 libstdc++-14-dev
   
4. Install audio support (optional)

   sudo apt install libpulse-dev
   

Arch Linux/Manjaro

sudo pacman -S --needed autoconf-archive base-devel ccache cmake curl git less libgl nasm ninja python qt6-base qt6-tools ttf-liberation tar unzip zip

Optionally, install the PulseAudio headers for audio playback support:

sudo pacman -S libpulse

Fedora

sudo dnf install autoconf-archive automake ccache cmake curl git libdrm-devel liberation-sans-fonts libglvnd-devel libtool nasm ninja-build patchelf perl-FindBin perl-IPC-Cmd perl-lib perl-Time-Piece qt6-qtbase-devel qt6-qttools-devel qt6-qtwayland-devel tar unzip zip zlib-ng-compat-static

openSUSE

sudo zypper install autoconf-archive automake ccache cmake curl gcc14 gcc14-c++ git liberation-fonts libglvnd-devel libtool nasm ninja qt6-base-devel qt6-tools-devel qt6-wayland-devel tar unzip zip

If base repository packages are flagged as having an out-of-date version during the build process, you may need to add the devel:tools:building repository.

For Leap 15.6:

sudo zypper addrepo https://download.opensuse.org/repositories/devel:tools:building/15.6/devel:tools:building.repo
sudo zypper refresh

Install audio support:

sudo zypper install libpulse-devel

Void Linux

sudo xbps-install -Su # (optional) ensure packages are up to date
sudo xbps-install -S git bash gcc python3 curl cmake libtool zip unzip linux-headers make pkg-config autoconf automake autoconf-archive nasm MesaLib-devel ninja qt6-base-devel qt6-tools-devel qt6-wayland-devel

macOS

Xcode 15 or clang from homebrew is required to successfully build ladybird.

xcode-select --install
brew install autoconf autoconf-archive automake ccache cmake libtool nasm ninja pkg-config

If you wish to use clang from homebrew instead:

brew install llvm@21

If you also plan to use the Qt UI on macOS:

brew install qt

It is recommended to add your terminal application (i.e. Terminal.app or iTerm.app) to the system list of developer tools. This will reduce slow startup time of freshly compiled binaries, due to macOS validating the binary on its first run.

This can be done in the “Developer Tools” section of the “Privacy & Security” system settings.

Windows

WSL2 (Recommended)

WSL2 is the supported way to build Ladybird on Windows. A native build is also possible, however it is still experimental.

1. Create a WSL2 environment

   Use one of the Linux distros listed above. Ubuntu or Fedora is recommended.

2. Install the required packages

   Install the required packages for the selected Linux distro in the WSL2 environment.

WSL1 is known to have issues. Please use WSL2. MinGW/MSYS2 are not supported.

Clang-CL (Experimental)

There are still windows specific issues and the functionality is limited.

Install pkg-config using Chocolatey:

choco install pkgconfiglite -y

Build using ladybird.py in a VS command prompt:

py Meta\ladybird.py build

Android

On a Unix-like platform, install the prerequisites for that platform and then see the Android Studio guide.

Or, download a version of Gradle >= 8.0.0, and run the gradlew program in UI/Android.

FreeBSD

pkg install autoconf-archive automake autoconf bash cmake curl gmake gn libdrm libtool libxcb libxkbcommon libX11 libXrender libXi nasm ninja patchelf pkgconf python3 qt6-base unzip zip

NixOS

A Nix development shell is maintained in the nix-environments repository.

If you encounter any problems building with Nix, please create an issue there.

---

Build steps

Using ladybird.py

The simplest way to build and run ladybird is via the ladybird.py script:

# From /path/to/ladybird
./Meta/ladybird.py run

Standard build

./Meta/ladybird.py run

macOS with homebrew clang

CC=$(brew --prefix llvm)/bin/clang CXX=$(brew --prefix llvm)/bin/clang++ ./Meta/ladybird.py run

Debug build

BUILD_PRESET=Debug ./Meta/ladybird.py run

Note that debug symbols are available in both Release and Debug builds.

With gdb

./Meta/ladybird.py gdb ladybird

If you want to run other applications, such as the JS REPL or the WebAssembly REPL, specify an executable with ./Meta/ladybird.py run <executable_name>.

The user interfaces

Ladybird will be built with one of the following browser frontends, depending on the platform:

• AppKit - The native UI on macOS
• Qt - The UI used on all other platforms
• Android UI - The native UI on Android

The Qt UI is available on platforms where it is not the default as well (except on Android). To build the Qt UI, install the Qt dependencies for your platform, and enable the Qt UI via CMake:

# From /path/to/ladybird
cmake --preset default -DENABLE_QT=ON

To re-disable the Qt UI, run the above command with -DENABLE_QT=OFF.

Custom CMake build directory

The script Meta/ladybird.py and the default preset in CMakePresets.json both define a build directory of Build/release. For distribution purposes, or when building multiple configurations, it may be useful to create a custom CMake build directory.

cmake --preset default -B MyBuildDir
# optionally, add -DCMAKE_CXX_COMPILER=<suitable compiler> -DCMAKE_C_COMPILER=<matching c compiler>
cmake --build --preset default MyBuildDir
ninja -C MyBuildDir run-ladybird

The install rules in UI/cmake/InstallRules.cmake define which binaries and libraries will be installed into the configured CMAKE_PREFIX_PATH or path passed to cmake --install.

Building with limited system memory

The default build mode will run as many build steps in parallel as possible, which includes link steps; this may be an issue for users with limited system memory.

If you wish to reduce the number of parallel link jobs, you may use the LAGOM_LINK_POOL_SIZE cmake option:

cmake --preset default -B MyBuildDir -DLAGOM_LINK_POOL_SIZE=2

Running manually

The Meta/ladybird.py script will execute the run-ladybird and debug-ladybird custom targets. If you don’t want to use the script, you can run the following commands:

gdb

ninja -C Build/release debug-ladybird

---

Resource files

Ladybird requires resource files from the ladybird/Base/res directory in order to properly load icons, fonts, and other theming information. These files are copied into the build directory by special CMake rules.

The expected location of resource files can be tweaked by packagers using the standard CMAKE_INSTALL_DATADIR variable. CMAKE_INSTALL_DATADIR is expected to be a path relative to CMAKE_INSTALL_PREFIX. If it is not, things will break.

---

Debugging

Debugging with CLion

Ladybird should be built with debug symbols first. This can be done by adding -DCMAKE_BUILD_TYPE=Debug to the cmake command line, or selecting the Build Type Debug in the CLion CMake profile.

After running Ladybird with ./Meta/ladybird.py run ladybird, you can use Run → Attach to Process in CLion to connect. If debugging layout or rendering issues, filter the listing for WebContent and attach to that.

Now breakpoints, stepping and variable inspection will work.

Debugging with Xcode or Instruments on macOS

If all you want to do is use Instruments, then an Xcode project is not required.

Simply run the ladybird.py script as normal, and then make sure to codesign the Ladybird binary with the proper entitlements to allow Instruments to attach to it:

./Meta/ladybird.py build
ninja -C Build/release apply-debug-entitlements
# or
codesign -s - -v -f --entitlements Meta/debug.plist Build/release/bin/Ladybird.app

Now you can open the Instruments app and point it to the Ladybird app bundle.

Building the project with Xcode is not supported. The Xcode project generated by CMake does not properly execute custom targets, and does not handle all target names in the project.

---

Common build errors

Unable to find a build program corresponding to “Ninja”

This error message is a red herring. We use vcpkg to manage our third-party dependencies, and this error is logged when something went wrong building those dependencies.

The output in your terminal will vary depending on what exactly went wrong, but it should look something like:

error: building skia:x64-linux failed with: BUILD_FAILED
Elapsed time to handle skia:x64-linux: 1.6 s

-- Running vcpkg install - failed
CMake Error at Toolchain/Tarballs/vcpkg/scripts/buildsystems/vcpkg.cmake:899 (message):
  vcpkg install failed.  See logs for more information:
  Build/release/vcpkg-manifest-install.log

If the error is not immediately clear from the terminal output, be sure to check the specified vcpkg-manifest-install.log for more information.

---

Experimental GN build

There is an experimental GN build for Ladybird. It is not officially supported, but it is kept up to date on a best-effort basis by interested contributors. See the GN build instructions in Meta/gn/README.md for more information.

In general, the GN build organizes ninja rules in a more compact way than the CMake build, and it may be faster on some systems. GN also allows building host and cross-targets in the same build directory, which is useful for managing dependencies on host tools when cross-compiling to other platforms.