Before releasing your Python package to the world, you need a safe place to test the publishing process. TestPyPI serves exactly this purpose. TestPyPI is a separate instance of the Python Package Index that acts as a sandbox environment. It allows you to upload, install, and test your packages without making them publicly available on the main PyPI site. This is especially helpful for catching issues in your package configuration, metadata, or distribution files before your official release. By using TestPyPI, you can ensure your package upload and installation workflow is smooth and error-free, reducing surprises when you publish to the real PyPI.

twine upload --repository testpypi dist/*