The development setup

To contribute to pretalx, it’s useful to run pretalx locally on your device so you can test your changes. First of all, you need install some packages on your operating system:

If you want to install pretalx on a server for actual usage, go to the Administrator documentation instead.

External dependencies

Please make sure you have the following dependencies installed:


Debian package

Python 3.6(!) or newer

pip for Python 3


python-dev for Python 3


python-venv, if not included








If your operating system does not provide Python 3.6 or newer, you might need to compile it yourself or install it from the unstable or experimental repositories.

Some Python dependencies might also need a compiler during installation, the Debian package build-essential or something similar should suffice.

Local Python environment

Please execute python -V or python3 -V to make sure you have Python 3.6 (or newer) installed. Also make sure you have pip for Python 3 installed, by running pip3 -V. Then use Python’s internal tools to create a virtual environment and activate it for your current session:

python3 -m venv env
source env/bin/activate

You should now see a (env) prepended to your shell prompt. You have to do this in every shell you use to work with pretalx (or configure your shell to do so automatically).

If you are working on Ubuntu or Debian, we strongly recommend upgrading your pip and setuptools installation inside the virtual environment, otherwise some of the dependencies might fail:

sudo pip3 install -U pip setuptools wheel

Get a copy of the source code

You can clone our git repository:

git clone
cd pretalx/

Working with the code

First up, install all the main application dependencies:

(env)$ cd src
(env)$ pip3 install -e ".[dev]"

Next, you will have to copy the static files from the source folder to the STATIC_ROOT directory, and create the local database:

(env)$ python collectstatic --noinput
(env)$ python migrate

To be able to log in, you should also create an admin user, organiser and team by running:

(env)$ python init

Additionally, if you want to get started with an event right away, run the create_test_event command:

(env)$ python create_test_event

This command will create a test event for you, with a set of test submissions, and speakers, and the like. With the --stage flag, you can determine which stage the event in question should be in. The available choices are cfp (CfP still open, plenty of submissions, but no reviews), review (submissions have been reviewed and accepted/rejected), schedule (there is a schedule and the event is currently running), and over. schedule is the default value.

If you want to see pretalx in a different language than English, you have to compile our language files:

(env)$ python compilemessages

If you need to test more complicated features, you should probably look into the setup documentation to find the bits and pieces you want to add to your development setup.

Run the development server

To run the local development server, execute:

(env)$ python runserver

Now point your browser to – You should be able to log in and play around!

Code checks and unit tests

Before you check in your code into git, always run the static linters and style checkers:

(env)$ black .
(env)$ isort .
(env)$ flake8 .

Once you’re done with those, run the tests:

(env)$ python -m pytest tests/

Pytest, our test framework, has a lot of useful options, like --lf to repeat only failing tests, -k something to run only tests called *something*, and -x to stop on the first breaking test.


If you have more than one CPU core and want to speed up the test suite, you can run python -m pytest -n NUM with NUM being the number of threads you want to use.

If you edit a stylesheet .scss file, please run sass-convert -i path/to/file.scss afterwards to format that file.

Working with mails

If you want to test emails in your development setup, we recommend starting Python’s debugging SMTP server in a separate shell and configuring pretalx to use it. The debugging SMTP server will print every email to its stdout.

Add this to your src/pretalx.cfg:

port = 1025

Then execute python -m smtpd -n -c DebuggingServer localhost:1025.

Working with translations

If you want to translate new strings that are not yet known to the translation system, you can use the following command to scan the source code for strings we want to translate and update the *.po files accordingly:

(env)$ python makemessages

To actually see pretalx in your language, you have to compile the *.po files to their optimised binary *.mo counterparts:

(env)$ python compilemessages

pretalx by default supports events in English, German, or French, or all three. To translate pretalx to a new language, add the language code and natural name to the LANGUAGES variable in the Depending on the completeness of your changes, and your commitment to maintain them in the future, we can talk about merging them into core.

Working with the documentation

To build the documentation, you will have to install the documentation dependencies. Go to the root directory of your git repository, and then run:

(env)$ pip install -Ur doc/requirements.txt

Then, to build the documentation, run the following command:

(env)$ make html

You will now find the generated documentation in the doc/_build/html/ subdirectory. If you find yourself working with the documentation more than a little, give the autobuild functionality a try:

(env)$ sphinx-autobuild . _build/html

Then, go to http://localhost:8081 for a version of the documentation that automatically re-builds when you save a changed source file. Please note that changes in the static files (stylesheets and JavaScript) will only be reflected after a restart.