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Before you can start contributing to CPython, you’ll need to set up your development environment. This guide will walk you through the process step by step.

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Prerequisites

Before you begin, make sure you have:
  • A Unix-like operating system (Linux, macOS, BSD, or Cygwin on Windows)
  • Git for version control
  • A C compiler (GCC or Clang)
  • Basic development tools (make, etc.)
For Windows development, see PCbuild/readme.txt for platform-specific instructions.

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Getting the Source Code

1

Fork the repository

Visit github.com/python/cpython and click the “Fork” button to create your own copy of the repository.
2

Clone your fork

git clone https://github.com/YOUR-USERNAME/cpython.git
cd cpython
3

Add upstream remote

git remote add upstream https://github.com/python/cpython.git
git fetch upstream

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Installing Dependencies

CPython requires various third-party libraries depending on your platform and configuration. Not all standard library modules are buildable on all platforms.

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Linux (Debian/Ubuntu)

sudo apt-get update
sudo apt-get install build-essential gdb lcov pkg-config \
      libbz2-dev libffi-dev libgdbm-dev libgdbm-compat-dev liblzma-dev \
      libncurses5-dev libreadline6-dev libsqlite3-dev libssl-dev \
      lzma lzma-dev tk-dev uuid-dev zlib1g-dev

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Linux (Fedora/RHEL)

sudo dnf install yum-utils gcc-c++ \
      bzip2-devel expat-devel gdbm-devel ncurses-devel openssl-devel \
      readline-devel sqlite-devel tk-devel xz-devel zlib-devel

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macOS

brew install openssl xz gdbm
macOS has additional configure and build options related to framework and universal builds. See Mac/README.rst for details.

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Configuring Your Workspace

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Editor Setup

CPython follows specific coding standards. Configure your editor to:
  • Use 4 spaces for indentation (not tabs)
  • Trim trailing whitespace
  • Use Unix-style line endings (LF)
  • Follow PEP 7 for C code and PEP 8 for Python code

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Git Configuration

# Set your name and email
git config user.name "Your Name"
git config user.email "[email protected]"

# Optional: Set up commit template
git config commit.template .gitmessage

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Verification

Verify your setup by running a quick configuration test: 
./configure --help
This should display available configuration options. If it works, you’re ready to build CPython!

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Troubleshooting

If ./configure doesn’t exist, you may need to generate it:
autoreconf -i
However, this is rarely needed as the configure script is committed to the repository.
macOS’s system OpenSSL may be outdated. Install via Homebrew and configure:
brew install openssl
./configure --with-openssl=$(brew --prefix openssl)
Ensure you have write permissions in the CPython directory. Avoid using sudo for build operations.

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Next Steps

Now that your environment is set up, you’re ready to:

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Additional Resources

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