PyPI

PyPI, the Python Package Index, is the official repository of third‑party software for Python. It serves as the central registry where developers publish packages and where users install them using package management tools such as pip. PyPI hosts thousands of projects ranging from small utilities to large frameworks, and it provides metadata for each package, including description, version, license, classifiers, and project URLs. The site is part of the broader Python packaging ecosystem and is complemented by tooling that supports packaging, distribution, and dependency resolution.

Packages on PyPI come in distribution formats such as source archives and prebuilt wheels. Each package version includes metadata that helps tools determine compatibility, dependencies, and installation requirements, including the Python version and required libraries. Tools and services can query PyPI via a simple index API and a JSON API to discover available versions.

Publishing to PyPI typically starts with creating a Python package locally, configuring packaging metadata in pyproject.toml or setup.cfg, building distribution files, and uploading them to PyPI with a tool such as Twine. Once uploaded and indexed, users can install the package using pip install package-name, optionally specifying a version or extras. PyPI also supports private projects and mirrored indexes to support offline or internal deployments.

Over time, PyPI has undergone modernization with a new web application and infrastructure to improve performance and security. It remains the primary distribution point for Python software and a central component of the Python ecosystem.