A list of issues and ongoing work is available on the PySTAC issues page. If you want to contribute code, the best way is to coordinate with the core developers via an issue or pull request conversation.

Development installation#

Fork PySTAC into your GitHub account. Then, clone the repo and install it locally with pip as follows:

$ git clone
$ cd  pystac
$ pip install -e .


PySTAC runs tests using unittest. You can find unit tests in the tests/ directory.

Run a single test with:

python -m unittest tests/

or an entire folder using:

python -m unittest discover -v -s tests/

or the entire project using:


The last command will also check test coverage. To view the coverage report, you can run coverage report (to view the report in the terminal) or coverage html (to generate an HTML report that can be opened in a browser).

More details on using unittest are here.

Code quality checks#

tl;dr: Run pre-commit install --overwrite to perform checks when committing, and ./scripts/test to run the tests.

PySTAC uses

  • black for Python code formatting

  • codespell to check code for common misspellings

  • doc8 for style checking on RST files in the docs

  • flake8 for Python style checks

  • mypy for Python type annotation checks

Run all of these with pre-commit run --all-files or a single one using pre-commit run --all-files ID, where ID is one of the command names above. For example, to format all the Python code, run pre-commit run --all-files black.

You can also install a Git pre-commit hook which will run the relevant linters and formatters on any staged code when committing. This will be much faster than running on all files, which is usually 1 only required when changing the pre-commit version or configuration. Once installed you can bypass this check by adding the --no-verify flag to Git commit commands, as in git commit --no-verify.


In rare cases changes to one file might invalidate an unchanged file, such as when modifying the return type of a function used in another file.


PySTAC maintains a changelog to track changes between releases. All PRs should make a changelog entry unless the change is trivial (e.g. fixing typos) or is entirely invisible to users who may be upgrading versions (e.g. an improvement to the CI system).

For changelog entries, please link to the PR of that change. This needs to happen in a few steps:

  • Make a PR to PySTAC with your changes

  • Record the link to the PR

  • Push an additional commit to your branch with the changelog entry with the link to the PR.

For more information on changelogs and how to write a good entry, see keep a changelog.