cfn-lint

Input—per 1M tokens

Output—per 1M tokens

Context—tokens

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About

cfn-lint is ranked #7 of 27 in infrastructure testing tools on Inferse. It runs on Linux, macOS, Self-hosted, Windows. There is a free plan.

Compared on infrastructure testing tools

Policy language: AWS CloudFormation Guard DSLgithub.com
IaC formats: CloudFormation templates and change sets; Terraform JSON; Kubernetes configurationsgithub.com
Policy testing: Yesgithub.com
Admission control: Yesgithub.com
Runtime enforcement: Nogithub.com
CI/CD integration: Yesgithub.com
Policy reporting: Yesgithub.com

Facts

Purpose: cfn-lint validates AWS CloudFormation YAML and JSON templates against resource provider schemas and additional checks, including valid property values and best practices.github.com · 2 Oct 2026
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.github.com · 2 Oct 2026
SAM support: The linter supports AWS Serverless Application Model templates by transforming them with AWS SAM before processing.github.com · 2 Oct 2026
Rules: The linter processes rules for specific checks and validations, and supports user-defined custom rules.github.com · 2 Oct 2026
Configuration: Users can configure cfn-lint with command-line options, configuration files, and CloudFormation template metadata.github.com · 2 Oct 2026
Output: Supported output formats include quiet, parseable, JSON, JUnit, pretty, and SARIF.github.com · 2 Oct 2026
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.github.com · 2 Oct 2026
Installation: The project documents installation with pip, Homebrew for macOS, or Docker.github.com · 2 Oct 2026
Runtime: The project states that Python 3.10 through 3.14 are supported.github.com · 2 Oct 2026
License: The repository identifies its license as MIT No Attribution, which grants use, copying, modification, distribution, sublicensing, and sale without restriction.github.com · 2 Oct 2026
Support: The project invites users to join its Discord community to discuss cfn-lint and get help.github.com · 2 Oct 2026
Who it serves: The project describes cfn-lint as a tool for validating AWS CloudFormation templates.github.com · 2 Oct 2026