No. 3 of 27 ·Infrastructure Testing Tools

cfn-lint

Windows · Mac · Linux · Self-hosted

Freedom report

Three barsScore 6.5

Free tierA free tier is on its own pricing page
Open codeNo open-source code on record
Runs widely3 of 6 device platforms
DocumentedPlans, terms and facts published

cfn-lint is ranked #3 of 27 in infrastructure testing tools on Freedom251. It runs on Linux, macOS, Self-hosted, Windows. There is a free plan.

cfn-lint plans and pricing

All plans

cfn-lint Free MIT-0 licensed · Python 3.10–3.14 supported github.com · 2 Oct 2026

Compared on infrastructure testing tools

Policy language: AWS CloudFormation Guard DSL
IaC formats: CloudFormation templates and change sets; Terraform JSON; Kubernetes configurations
Policy testing: Yes
Admission control: Yes
Runtime enforcement: No
CI/CD integration: Yes
Policy reporting: Yes

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The record

Purpose: cfn-lint validates AWS CloudFormation YAML and JSON templates against resource provider schemas and additional checks, including valid property values and best practices.
Validation caveat: The project describes validation of complex template values as best effort and says it will not fail just because it cannot understand or translate them.
SAM support: The linter supports AWS Serverless Application Model templates by transforming them with AWS SAM before processing.
Rules: The linter processes rules for specific checks and validations, and supports user-defined custom rules.
Configuration: Users can configure cfn-lint with command-line options, configuration files, and CloudFormation template metadata.
Output: Supported output formats include quiet, parseable, JSON, JUnit, pretty, and SARIF.
Integrations: The project lists editor integrations for Atom, Emacs, NeoVim/Vim, Sublime, Visual Studio Code, and IntelliJ IDEA, plus a GitHub Action and pre-commit hook.
Installation: The project documents installation with pip, Homebrew for macOS, or Docker.
Runtime: The project states that Python 3.10 through 3.14 are supported.
License: The repository identifies its license as MIT No Attribution, which grants use, copying, modification, distribution, sublicensing, and sale without restriction.
Support: The project invites users to join its Discord community to discuss cfn-lint and get help.
Who it serves: The project describes cfn-lint as a tool for validating AWS CloudFormation templates.
Price from: Free

Where it ranks on Freedom251

Best Infrastructure Testing Tools in 2026#3 of 27
Best Infrastructure Policy as Code Tools in 2026#6 of 24

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Sources

github.com/aws-cloudformation/cfn-lint· checked 2 Oct 2026
github.com/aws-cloudformation/cfn-lint/blob/main/L· checked 2 Oct 2026