cfn-lint

Checks CloudFormation templates for practices and behaviour that could potentially be improved

cfn-lint Permissive license MIT-0 Active ★ 2,638 v1.55.1 released 2026-08-13

Install

cfn-lint on PyPI

pip

pip install cfn-lint

uv

uv add cfn-lint

poetry

poetry add cfn-lint

Package facts

License	MIT-0 (permissive)
Python support	supports the current Python release (<3.15,>=3.10)
Install friction	low — pure-Python wheel
Runtime dependencies	6 — pyyaml, jsonpatch, networkx, sympy, regex, typing_extensions
Maintenance	actively maintained — 0 days since the last release
Last repo commit	2026-08-13
First released	2018-04-17
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: cfn_lint-1.55.1-py3-none-any.whl

Keywords: aws, cloudformation, lint

Development Status :: 5 - Production/StableIntended Audience :: DevelopersNatural Language :: EnglishOperating System :: OS IndependentProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14

About cfn-lint

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

AWS CloudFormation Linter

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Validate AWS CloudFormation yaml/json templates against the AWS CloudFormation resource provider schemas and additional checks. Includes checking valid values for resource properties and...

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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

Validates AWS CloudFormation templates in YAML or JSON against AWS resource schemas and best practices, checking property values and compliance with CloudFormation rules.

Low friction: pure Python wheel with six stable runtime dependencies (pyyaml, jsonpatch, networkx, sympy, regex, typing_extensions). Actively maintained with a release on 2026-08-13.

MIT-0 (permissive) allows unrestricted use, modification, and distribution with no attribution requirement—ideal for both commercial and open-source projects.

Usage

pip install cfn-lint
cfn-lint template.yaml

Requires Python 3.10–3.14; cfn-lint is a CLI tool, not a library with typical import/call patterns.

Verdict: Production-ready linter for CloudFormation templates with active maintenance, permissive licensing, and low install friction. No known vulnerabilities. Well-suited for CI/CD pipelines and local validation workflows.

Needs verification

Whether the six runtime dependencies introduce any transitive vulnerabilities or breaking changes in their own maintenance.
Performance characteristics on very large or deeply nested CloudFormation templates.
Coverage and accuracy of the linter's best-practice checks relative to current AWS CloudFormation guidance.
Repository activity level and community engagement beyond the latest release date.

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