Source code

Pontoon source code is available via GitHub:


Our work is tracked in GitHub.

Report a new issue:


Everything runs in a Docker container. Thus Pontoon requires fewer things to get started and you’re guaranteed to have the same setup as everyone else and it solves some other problems, too.

If you’re not familiar with Docker and docker-compose, it’s worth reading up on.


By default, you will have default data loaded for only the Pontoon Intro project. If you have a database dump, you can load it into your PostgreSQL database.

Make sure you backup your existing database first:

$ make dumpdb

And then load the dump:

$ make loaddb DB_DUMP_FILE=path/to/my/dump

Note that your database container needs to be running while you do that. You can start just the postgresql container by running:

$ docker-compose run postgresql -d

Interactive shell

If you need to run specific commands, that are not covered by our Makefile, you can start an interactive shell inside a Pontoon container:

$ make shell

Browser Support

The list of browsers supported by Pontoon is defined in the “browserslist” entry of the root package.json, and contains by default:

Firefox >= 78
Chrome >= 80
Edge >= 91
Safari >= 13.1

Code style

We use code formatters so that we do not have to fight over code style. You are free to write code however you like, because in the end the formatter is the one that will format it. We thus don’t need to pay attention to style during code reviews, and are free from those never-ending code style discussions.

To format the Python and the JavaScript code at once you can use:

$ make format

Code formatting is explained in more detail in the following sections.

To run the required linters on the Python and the Javascript code at once you can use:

$ make lint

Python code conventions

Our Python code is automatically formatted using black. We enforce that in our Continuous Integration, so you will need to run black on your code before sending it for review.

You can run black locally either as an add-on in your code editor, or as a git pre-hook commit. Alternatively, you can format your code using:

$ make black

We also require Python code to use newer syntax of Python. You can upgrade automatically by running:

$ make pyupgrade

Additionally, we use a linter to verify that imports are correct. You can run it with:

$ make flake8

In the rare case when you cannot fix a flake8 error, use # noqa to make the linter ignore that error. Note that in most cases, it is better to fix the issues than ignoring them.

Javascript code conventions

Our Javascript code is automatically formatted using Prettier. We enforce that in our Continuous Integration, so you will need to run prettier on your code before sending it for review.

You can run prettier locally either as an add-on in your code editor, or as a git pre-hook commit. Alternatively, you can format your code using:

$ make prettier

Additionally, there are linting rules that are defined in our .eslintrc.js file. To run the linter, do:

$ make eslint

In the rare case when you cannot fix an eslint error, use // eslint-disable to make the linter ignore that error. Note that in most cases, it is better to fix the issues than ignore them.

For more specifics about the `frontend folder, look at the file there.

Git conventions

The first line is a summary of the commit. It should start with one of the following:

Fix #1234



The first, when it lands, will cause the issue to be closed. The second one just adds a cross-reference.

After that, the commit should explain why the changes are being made and any notes that future readers should know for context or be aware of.

We follow The seven rules of a great Git commit message:

  1. Separate subject from body with a blank line
  2. Limit the subject line to 50 characters
  3. Capitalize the subject line
  4. Do not end the subject line with a period
  5. Use the imperative mood in the subject line
  6. Wrap the body at 72 characters
  7. Use the body to explain what and why vs. how

Pull requests

Pull request summary should indicate the issue the pull request addresses.

Pull request descriptions should cover at least some of the following:

  1. what is the issue the pull request is addressing?
  2. why does this pull request fix the issue?
  3. how should a reviewer review the pull request?
  4. what did you do to test the changes?
  5. any steps-to-reproduce for the reviewer to use to test the changes

Code reviews

Pull requests should be reviewed before merging.

Style nits should be covered by linting as much as possible.

Code reviews should review the changes in the context of the rest of the system.


Direct dependencies for Pontoon are distributed across four files:

  1. requirements/ Running Pontoon in production
  2. requirements/ Development
  3. requirements/ Testing
  4. requirements/ Linting

In order to pin and hash the direct and indirect dependencies, we use pip-compile, which yields corresponding *.txt files. These *.txt files contain all direct and indirect dependencies, and can be used for installation with pip. After any change to the *.in files, you should run the following command to update all requirements/*.txt files.

$ make requirements

When adding a new requirement, add it to the appropriate requirements/*.in file. For example, to add the development dependency foobar version 5, add foobar==5 to requirements/, and then run the command from above.

Once you are done adding, removing or updating requirements, rebuild your docker environment:

$ make build-server

If there are problems, it’ll tell you.

To upgrade existing dependencies within the given constraints of the input files, you can pass options through to the pip-compile invocations, i.e.

$ make requirements opts=--upgrade


Documentation for Pontoon is built with Sphinx and is available on ReadTheDocs.

Building docs is not covered with docker yet, so you will have to do it on your host. To make a virtualenv to build docs, do this:

$ cd docs/
$ virtualenv venv
$ source venv/bin/activate
$ pip install --require-hashes -r requirements.txt

Then, to build the docs, run this:

$ make html

The HTML documentation will be in docs/_build/html/. Try to open docs/_build/html/index.html for example.


Pontoon uses GraphViz as part of the documentation generation, so you’ll need to install it to generate graphs that use it. Most package managers, including Homebrew, have a package available for install.

Running tests

To run the entire test suite, do:

$ make test

To run only the frontend tests:

$ make jest

To run only the Python tests:

$ make pytest

To run specific tests or specify arguments, you’ll want to start a shell in the test container:

$ make shell

Then you can run tests as you like.

Running all the unittests (make sure you run ./ collectstatic first):

app@...:/app$ pytest

Running a directory of tests:

app@...:/app$ pytest pontoon/base/

Running a file of tests:

app@...:/app$ pytest pontoon/base/tests/

Writing tests

Put your tests in the tests/ directory of the appropriate app in pontoon/.

Mock usage

Mock is a python library for mocks objects. This allows us to write isolated tests by simulating services besides using the real ones. Best examples are existing tests which admittedly do mocking different depending on the context.

Tip! Try to mock in limited context so that individual tests don’t affect other tests. Use context managers instead of monkey patching imported modules.

Updating Your Local Instance

When changes are merged into the main Pontoon repository, you’ll want to update your local development instance to reflect the latest version of the site. You can use Git as normal to pull the latest changes, but if the changes add any new dependencies or alter the database, you’ll want to install any new libraries and run any new migrations.

If you’re unsure what needs to be run, it’s safe to just perform all of these steps, as they don’t affect your setup if nothing has changed:

# Pull the latest code (assuming you've already checked out master).
git pull origin master

# Install new dependencies or update existing ones.
pip install -U --force --require-hashes -r requirements/default.txt

# Run database migrations.
python migrate

Building front-end resources

We use webpack to build our JavaScript files for some pages (currently only the tag admin UI). While make build will build those files for you, you might want to rebuild them while programming on the front. To build the files just once, run:

$ make build-tagadmin

If you want to have those files be built automatically when you make changes, you can run:

$ make build-tagadmin-w