Developing Jupytext

How to test development versions from GitHub

If you want to test a feature that has been integrated in main but not delivered yet to pip or conda, use

pip install git+

If you want to test Jupytext in JupyterLab 3 then you will have to build the extension for JupyterLab. To do so, make sure that you have a recent version of node, and prefix the command above with BUILD_JUPYTERLAB_EXTENSION=1.

Finally, if you want to test a development branch, use

pip install git+

where branch is the name of the branch you want to test (again, prefix the command above with BUILD_JUPYTERLAB_EXTENSION=1 if you want to use Jupytext within JupyterLab 3).

Install and develop Jupytext locally

Most of Jupytext’s code is written in Python. To develop the Python part of Jupytext, you should clone Jupytext, then create a dedicated Python env:

cd jupytext
conda env create --file environment.yml  # or conda env update --file ...
conda activate jupytext-dev
python -m ipykernel install --name jupytext-dev --user
pip install -e .

We use the pre-commit package to run pre-commit scripts like black and flake8 on the code. Install it with

pre-commit install

Tests are executed with pytest. You can run them in parallel with for instance

pytest -n 5

We also have a tox.ini file available if you wish to test your contribution on multiple version of Python before making a PR - just run tox.

Build the jupytext package and install it with

BUILD_JUPYTERLAB_EXTENSION=1 python sdist bdist_wheel
pip install dist/jupytext-x.x.x-py3-none-any.whl

or with


Finally, note that you can remove BUILD_JUPYTERLAB_EXTENSION=1 if you don’t need the lab extension, and if you don’t want to install nodejs or if you want a faster build.

Jupytext’s extension for Jupyter Notebook

Our extension for Jupyter Notebook adds a Jupytext entry to Jupyter Notebook Menu. The code is found at jupytext/nbextension/index.js. Instructions to develop that extension are at jupytext/nbextension/

Jupytext’s extension for JupyterLab

Our extension for JupyterLab adds a series of Jupytext commands to JupyterLab. The code is in packages/labextension. See the there for instructions on how to develop that extension.

Jupytext’s documentation

Install the documentation tools with

conda env create --file docs/environment.yml
conda activate jupytext-docs
cd docs

and build the HTML documentation locally with

rm -rf _build
make html