yamllint

A linter for YAML files.

yamllint Copyleft license GPL-3.0-or-later Active ★ 3,446 v1.38.0 released 2026-01-13

Install

yamllint on PyPI

pip

pip install yamllint

uv

uv add yamllint

poetry

poetry add yamllint

Package facts

License	GPL-3.0-or-later (copyleft)
Python support	supports the current Python release (>=3.10)
Install friction	low — pure-Python wheel
Runtime dependencies	2 — pathspec, pyyaml
Maintenance	actively maintained — 212 days since the last release
Last repo commit	2026-07-20
First released	2016-01-12
Popularity	one of the top 1,000 most-downloaded packages on PyPI (30-day window, as of 2026-08-13)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-13)

Evidence: yamllint-1.38.0-py3-none-any.whl

Keywords: yaml, lint, linter, syntax, checker

Development Status :: 5 - Production/StableEnvironment :: ConsoleIntended Audience :: DevelopersProgramming Language :: PythonTopic :: Software DevelopmentTopic :: Software Development :: DebuggersTopic :: Software Development :: Quality AssuranceTopic :: Software Development :: Testing

About yamllint

from the package's own PyPI description — quoted content, verbatim

yamllint

A linter for YAML files.

yamllint does not only check for syntax validity, but for weirdnesses like key repetition and cosmetic problems such as lines length, trailing spaces, indentation, etc.

.. image:: https://github.com/adrienverge/yamllint/actions/workflows/tests.yaml/badge.svg?branch=master :target: https://github.com/adrienverge/yamllint/actions/workflows/tests.yaml?query=branch%3Amaster :alt: CI tests status .. image:: https://coveralls.io/repos/github/adrienverge/yamllint/badge.svg?branch=master :target: https://coveralls.io/github/adrienverge/yamllint?branch=master :alt: Code coverage status .. image:: https://readthedocs.org/projects/yamllint/badge/?version=latest :target: https://yamllint.readthedocs.io/en/latest/?badge=latest :alt: Documentation status

Written in Python.

Documentation

https://yamllint.readthedocs.io/

Overview

Screenshot ^^^^^^^^^^

.. image:: docs/screenshot.png :alt: yamllint screenshot

Installation ^^^^^^^^^^^^

Using pip, the Python package manager:

.. code:: bash

pip install --user yamllint

yamllint is also packaged for all major operating systems, see...

Read as markdown · JSON record · Source repository · Docs

AI interpretation — verify before relying

AI-generated interpretation of the package facts above; every digit, version, license, or vulnerability id it cites is grounded in the facts already shown on this page

yamllint is a YAML linter that checks syntax validity and enforces style rules like indentation, line length, trailing spaces, and key duplication across YAML files.

Low friction: pure Python wheel with only two runtime dependencies (pathspec, pyyaml). Active maintenance with last commit on 2026-07-20 and 3446 GitHub stars.

GPL-3.0-or-later copyleft license requires derivative works and modifications to be released under the same license; suitable for open-source projects but may conflict with proprietary software policies.

Usage

pip install yamllint
yamllint my_file.yaml
# or with custom config:
yamllint -c /path/to/config.yaml my_file.yaml

Requires Python 3.10 or later.

Verdict: yamllint is a stable, actively maintained YAML linter in the top 1000 PyPI packages with minimal dependencies and no known vulnerabilities. Its GPL-3.0-or-later copyleft license is appropriate for open-source workflows but requires license review in proprietary contexts.

Needs verification

Whether the GPL-3.0-or-later license applies to configuration files or only to code modifications.
Performance characteristics when linting large YAML file collections or deeply nested structures.

yaml linteryaml syntax checkeryaml style enforceryaml code qualityyaml validation toolyaml formatting checkeryaml lint rules