Building Pale Moon: Microsoft Windows

These instructions are for building Pale Moon 29.4.1 and newer and assumes you want to build the latest release.


  • Microsoft Visual Studio 2015 (Community Edition (free) or Pro/Paid version -- Express won't work) with updates
  • Exactly Windows 10 SDK version 10.0.19041.0 (with servicing update .685)
  • GoannaBuild 2.3.8054. This is an all-in-one build package with software licensed under various Open Source and permissive licenses. See the individual components in the package after extraction for details.
  • At least 6 GB RAM (8 GB or more recommended, especially if building parallel)
  • Plenty of free disk space
  • At least Windows 7 64-bit (32-bit build environments are not supported)
  • Modern 7-zip or another archiver capable of reading 7z files if using a source archive (deprecated since 30.0.0)


To get the free Visual Studio 2015 Community Edition you need a Developer Account (simply a Microsoft account). Microsoft will try to push newer versions of Visual Studio but it must be exactly VS 2015 with Update 3. You will have to get this version from the "previous versions" part of the site.

Launch Visual Studio 2015 after installation to initialize the environment, start the IDE and get the latest updates. Launch after updating to finish up the update, after which you can close the IDE. For x64 builds, make sure you install the x64 build tools.
Note: You will be asked to register with Microsoft when launching it the first time; simply log in with your developer account in the IDE and you're set.

Make sure you install the correct components for "C++ development"; other languages are not necessary and not installing them will save you (heaps of) disk space.

Getting the source

These instructions will assume you are going to create a directory on your C drive called palemoon-source. You can, of course, put the source code anywhere you want as long as the path does not contain any spaces.

Using git

Git is the official way to get the Pale Moon source code from our repository server and to build.

  • Install git and open a Git Bash prompt, and change directory to the desired source location, e.g.
    cd /location-you-picked/palemoon-source/
  • Execute the following commands:
    git clone ./
    git submodule init && git submodule update
    git checkout release && git submodule update
  • Close Git Bash and proceed to the "Build instructions" below.

Using the source archives

These instructions are for building Pale Moon 29.4.1 to 29.4.4 as well as older versions that were released as source code snapshot archives.

This requires downloading source archives from the Pale Moon Archive Server:

  • Navigate to the source directory on the Archive Server and download the desired version of the source tarball.
  • The archive filename is in the following format (where n.n.n is the Pale Moon version):
  • Extract the source code to the desired location.
  • Proceed to the "Build instructions" below.

Build instructions


Create a file called .mozconfig in the source folder you cloned or unpacked the source to.

(Yes, that is {dot}mozconfig -- don't omit the . at the start. Also make sure it's not .mozconfig.txt or something crooked like that. If you are hiding extensions of known file types, fix that first in folder options because it's a PITA when trying to do this kind of thing)

Make sure it contains at least the following for a close-to-official build excluding updater:

.mozconfig file

# Set to 1 if you want a 64 bit build else leave as-is

# Standard build options for Pale Moon
ac_add_options --enable-application=palemoon
ac_add_options --enable-optimize="-O2 -GS-"
ac_add_options --enable-jemalloc
ac_add_options --enable-strip
ac_add_options --enable-devtools
ac_add_options --enable-av1
ac_add_options --disable-accessibility
ac_add_options --disable-gamepad
ac_add_options --disable-parental-controls
ac_add_options --disable-tests
ac_add_options --disable-debug
ac_add_options --disable-updater

# Please see for restrictions when using the official branding.
ac_add_options --enable-official-branding

# Processor architecture specific build options
if [ -n "$_BUILD_64" ]; then

# Visual C++ redist files
WIN_UCRT_REDIST_DIR="C:/Program Files (x86)/Windows Kits/10/Redist/10.0.19041.0/ucrt/DLLs/$_BUILD_ARCH"

Note: less is more! There are some pre-made build configs out there that have a lot of options listed, often with insane resulting build configurations. Do not use those and stick to the instructions here.

Note: Please check the Visual C++ redist directories. If you use MozillaBuild 3.0 or later, $VCINSTALLDIR will not be defined and you will have to indicate a full path. If you build with a different Win 10 SDK version (e.g. the one included with VS2015 or an earlier/later version -- not recommended) or have installed the SDK in a different path than the default, then you need to adjust the mozconfig path to the UCRT DLLs accordingly.


  • Go to C:\mozilla-build (or wherever you extracted the Goanna build tools) and run
    • This will open a UNIX-like shell with the compile environment set up for Visual Studio 2015 with a 32-bit target. Please do not use the -x64 batch file even if you are on a 64-bit operating system when building x86.
    • The -x64 batch file is for launching a 64-bit build environment and building a 64-bit browser. So for creating an x64 build of Pale Moon, run
  • In the shell, cd to your Pale Moon source directory, e.g.
    cd /c/palemoon-source
  • Start the build:
    ./mach build

Be patient. Building will take a long time. Your PC will be fully occupied compiling and linking the browser (you can expect 100% CPU usage throughout and lots of memory use - provide ample cooling) and you should not be using it for anything else that is resource-intensive at this time. Especially memory-intensive applications should be avoided because it can cause issues with the linker (memory fragmentation) resulting in a very unstable browser.

Important note: before you start building, make sure to exclude the source and target folders from antivirus software or it will severely slow down the build process or may even break it entirely (due to file locks). Either completely disable real-time/on-access scanning before building, or make specific exclusions for your working folders.


After building is completed, you can take the resulting binaries for a test run in the object directory directly (see the on-screen instructions at the end of the build process) but it will not be complete yet. You need to strip and package the browser to integrate additional code, pack up the resource files, and have a ready-to-use browser. You do this by running:

./mach package
This will create a properly packaged .zip file in your object folder under the Pale Moon source folder. e.g. for x86:

Generating the installer

If you want to build a self-extracting installer, similar to the off-line installers offered in official builds, you will have to do give the following command:

./mach installer
This will create a self-extracting installer in your object folder under the Pale Moon source folder. e.g. for x86:

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