---
id: stdlibs
version: "2026.2.26"
license: unclear
license_treatment: permissive
maintenance: active
---

# stdlibs — List of packages in the stdlib

License: permissive · Maintenance: active · Downloads: 2.7M/mo

## What it is and what it does

stdlibs is a reference package that maintains a static inventory of Python standard library modules across multiple CPython versions. It solves the problem of determining which modules are part of the standard library for a given Python version—useful for static analysis tools, linters, and import sorters that need to distinguish standard library imports from third-party ones.

The package provides module name lists for each major CPython release from 2.3 onward, plus combined views across all 2.x and 3.x releases. On Python 3.10+, the runtime provides `sys.stdlib_module_names`, but stdlibs exists to offer historical records, pre-release listings, and a broader set of importable modules that aren't always included in the official runtime list. It's used by tools like Ruff and µsort.

Use it for:

- Determine whether a module name belongs to the standard library for a specific Python version in static analysis.
- Track which stdlib modules were added or removed between Python versions for compatibility checking.
- Distinguish standard library imports from third-party packages in import sorting and linting tools.
- Generate diffs of stdlib module availability across Python versions for documentation or tooling.
- Support pre-3.10 Python versions where `sys.stdlib_module_names` is unavailable.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides a static listing of all known modules in Python's standard library, with separate lists for each major CPython release dating back to Python 2.3.

Yes. This is a lightweight, actively maintained reference package with zero dependencies, permissive licensing, and clear utility for static analysis and tooling. Install it if you're building linters, import sorters, or any tool that needs to reliably distinguish standard library modules from third-party ones across multiple Python versions.

## Install

pip install stdlibs
uv add stdlibs
poetry add stdlibs

## Installing stdlibs

Before you install: Low install friction with no runtime dependencies. Actively maintained; last release 169 days ago with repository activity as recent as 2026-07-01.

License in practice: Licensed under MIT (permissive), allowing use in both open-source and proprietary projects with minimal restrictions.

Quickstart:

pip install stdlibs

from stdlibs import module_names
print("os" in module_names)  # True

from stdlibs.py36 import module_names as py36_names
print("zoneinfo" in py36_names)  # False

Requires Python 3.8 or newer.

Verify before relying:

- Whether the package captures all private/importable modules that ship with stable CPython releases as claimed in the description.

## Package facts

- License: not declared (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 2.7M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

python stdlib module names, standard library listing, cpython module inventory, stdlib version history, check if module is builtin, python standard library reference, static-analysis, stdlib-reference

[View on SkillFed](https://skillfed.io/packages/stdlibs) · [View on PyPI](https://pypi.org/project/stdlibs/)