Font Tools

fontTools Developer Information

If you would like to contribute to the development of fontTools, you can clone the repository from GitHub, install the package in ‘editable’ mode and modify the source code in place. We recommend creating a virtual environment, using the Python 3 venv module:

# download the source code to 'fonttools' folder
git clone
cd fonttools

# create new virtual environment called e.g. 'fonttools-venv', or anything you like
python -m venv fonttools-venv

# source the `activate` shell script to enter the environment (Un*x)
. fonttools-venv/bin/activate

# to activate the virtual environment in Windows `cmd.exe`, do

# install in 'editable' mode
pip install -e .


To exit a Python virtual environment, enter the command deactivate.


To run the test suite, you need to install pytest. When you run the pytest command, the tests will run against the installed fontTools package, or the first one found in the PYTHONPATH.

You can also use tox to automatically run tests on different Python versions in isolated virtual environments:

pip install tox


When you run tox without arguments, the tests are executed for all the environments listed in the tox.ini envlist. The Python versions that are not available on your system PATH will be skipped.

You can specify a particular testing environment list via the -e option, or the TOXENV environment variable:

tox -e py36
TOXENV="py36-cov,htmlcov" tox

Development Community

fontTools development is ongoing in an active community of developers that includes professional developers employed at major software corporations and type foundries as well as hobbyists.

Feature requests and bug reports are always welcome at

The best place for end-user and developer discussion about the fontTools project is the fontTools gitter channel. There is also a development mailing list for continuous integration notifications.


The fontTools project was started by Just van Rossum in 1999, and was maintained as an open source project at In 2008, Paul Wise (pabs3) began helping Just with stability maintenance. In 2013 Behdad Esfahbod began a friendly fork, thoroughly reviewing the codebase and making changes at to add new features and support for new font formats.


In alphabetical order:

Olivier Berten, Samyak Bhuta, Erik van Blokland, Petr van Blokland, Jelle Bosma, Sascha Brawer, Tom Byrer, Frédéric Coiffier, Vincent Connare, Dave Crossland, Simon Daniels, Peter Dekkers, Behdad Esfahbod, Behnam Esfahbod, Hannes Famira, Sam Fishman, Matt Fontaine, Yannis Haralambous, Greg Hitchcock, Jeremie Hornus, Khaled Hosny, John Hudson, Denis Moyogo Jacquerye, Jack Jansen, Tom Kacvinsky, Jens Kutilek, Antoine Leca, Werner Lemberg, Tal Leming, Peter Lofting, Cosimo Lupo, Masaya Nakamura, Dave Opstad, Laurence Penney, Roozbeh Pournader, Garret Rieger, Read Roberts, Guido van Rossum, Just van Rossum, Andreas Seidel, Georg Seifert, Chris Simpkins, Miguel Sousa, Adam Twardoch, Adrien Tétar, Vitaly Volkov, Paul Wise.


MIT license. See the full text of the license for details.