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Build instructions

Table of contents:

Preface

These instructions are for CEF Python v147+, which uses CMake for compilation and tools/build_distrib.py for wheel packaging. The workflow is driven by the helper scripts described below. For older releases (v50-v123) see the build instructions in that release's branch/tag - the build system was substantially rewritten for v147 and the old instructions no longer apply.

Supported platforms, matching what CI builds and tests on every push (see .github/workflows/):

  • Windows x64
  • Linux x64
  • macOS (Apple Silicon / arm64)

Supported Python versions: 3.10 - 3.14.

Before building you must satisfy the platform-specific requirements listed below.

Requirements

Windows

  • Python 3.10+ (64-bit).
  • Visual Studio 2022 or later with the "Desktop development with C++" workload. See https://wiki.python.org/moin/WindowsCompilers for which VS version is required by your Python version.
  • CMake and Ninja are installed into the active Python environment in step 1 below; no separate system installation is required.

Linux

  • Python 3.10+ (64-bit). Tested on Ubuntu 24.04.
  • Install the packages in the "Install system dependencies" step of ci-linux.yml to compile cefpython.
  • To run cefpython on a minimal system or under Xvfb, also install the packages in that workflow's "Install runtime dependencies" step. The workflow is the authoritative, tested package list so it does not drift from this guide.

macOS

  • Python 3.10+ (arm64/Apple Silicon) on macOS 12 or later. Tested on macOS 14.
  • Xcode with command line tools installed (xcode-select --install).
  • CMake and Ninja are installed into the active Python environment in step 1 below; no separate system installation is required.
  • Ad-hoc code signing is done automatically by the build (via the system codesign tool) so that macOS allows the built binaries to run.

Quick build

git clone https://github.com/cztomczak/cefpython.git
cd cefpython/
git checkout cefpython147
python -m venv .venv

Activate the virtual environment:

# Windows Command Prompt (including a Visual Studio Developer Command Prompt)
.venv\Scripts\activate.bat

# Windows PowerShell
.\.venv\Scripts\Activate.ps1

# Linux or macOS
. .venv/bin/activate

Then install the build dependencies and build:

python tools/requirements.py
python tools/download_cef.py
python tools/automate.py --prebuilt-cef
python tools/build.py --unittests

This downloads and prepares the matching CEF binaries for your platform, builds the cefpython extension module, and runs the unit test suite. See below for what each step does and the available options.

Build steps in detail

1. Install Python build tools

Create and activate a virtual environment as shown in the quick build, or activate an existing environment, then run:

python tools/requirements.py

This helper uses the active Python interpreter to install Cython, scikit-build-core, CMake, Ninja and the other build-time dependencies listed in tools/requirements.txt into the active Python environment. No separate system installation of CMake or Ninja is required; activating the environment places their executables on PATH. Re-run this after pulling changes because the build requirements may change.

2. Get CEF binaries

python tools/download_cef.py
python tools/automate.py --prebuilt-cef

tools/download_cef.py reads the required CEF version from src/version/cef_version_*.h, downloads the matching distribution from Spotify Automated Builds, verifies its checksum, and extracts it into build/.

tools/automate.py --prebuilt-cef then builds the CEF wrapper library and prepares the build/cef<version>_<platform>/ directory that tools/build.py expects. It does not download CEF itself.

To download without preparing (e.g. to inspect the archive first), or to download for a different platform than the one you're on, see python tools/download_cef.py --help.

3. Build cefpython

python tools/build.py

By default this runs a fast CMake dev build: it configures (first run only) and builds build/_cmake_build/, then copies the extension module, the subprocess executable, and the CEF runtime files into cefpython3/ so that import cefpython3 works directly from the repo.

Useful flags (see python tools/build.py docstring for the full list):

  • --clean - delete the CMake build directory first (full rebuild).
  • --unittests - run the unit test suite after building.
  • --wheel - additionally build an installable wheel and install it (see Build a wheel package).
  • --enable-profiling / --enable-line-tracing - Cython cProfile / line-tracing instrumentation, for profiling or coverage.

4. Run unit tests

python tools/build.py --unittests

or, if you've already built:

python unittests/_test_runner.py

On Linux this requires a display - either a real one or Xvfb: xvfb-run python unittests/_test_runner.py.

5. Build a wheel package

python tools/build.py --wheel

This packages the already-built (and, on macOS, already-signed) tree in cefpython3/ into a wheel under build/dist/, using tools/build_distrib.py, and installs it with python -m pip install --force-reinstall.

CI currently executes the configure, build, staging, and packaging steps explicitly, invoking tools/build_distrib.py --dev for commit-identifiable wheels. Consolidating this workflow behind a standards-compliant Python build backend is deferred to a follow-up task.

To smoke-test a built wheel the way CI does (install it, then launch and auto-close a couple of the example apps):

python tools/smoke_test.py