cfn-lint review

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

cfn-lint is an open-source command-line linter for AWS CloudFormation templates written in YAML or JSON. It is aimed at developers and infrastructure teams that want to identify template problems before deployment, whether locally, in a CI/CD workflow, or from an editor. The tool checks syntax, resource properties, supported values, deployment-related errors, and best-practice findings. It also supports AWS SAM templates, making it relevant to serverless infrastructure workflows built on CloudFormation.

Its strongest area is validation depth within the CloudFormation model. cfn-lint checks templates against CloudFormation resource provider schemas, can run checks for multiple AWS Regions, and supports custom rules, external rule sets, and custom CloudFormation specification overrides. That gives teams room to adapt validation to regional differences or internal standards. Output options include quiet, parseable, JSON, JUnit, pretty, and SARIF formats, which suit both human review and automated CI reporting. Integrations include GitHub Actions, pre-commit, Docker, and editors such as Visual Studio Code, Emacs, Neovim, Vim, Sublime Text, and IntelliJ IDEA.

The product is free and open source, with local execution across macOS, Linux, and Windows. It can be distributed as a Python package, installed with Homebrew, or run in Docker. That makes it a practical fit for teams that want validation embedded in existing development pipelines rather than a hosted service. Its scope is also clear: cfn-lint validates templates, but it does not provision infrastructure or test deployed environments. Teams needing runtime verification, provisioning tests, or broader cloud coverage should choose a tool with those capabilities instead. For pre-deployment CloudFormation checks, especially in CI, cfn-lint is a focused choice.

cfn-lint pros and cons

• Where it wins
  • Validates templates against CloudFormation resource provider schemas
  • Supports AWS SAM, multiple Regions, custom rules, and specification overrides
  • Fits CI and editor workflows with JSON, JUnit, SARIF, and other outputs
• Where it doesn't
  • Does not perform provisioning tests
  • Does not test deployed infrastructure
  • Focused on AWS CloudFormation and AWS SAM

cfn-lint fact sheet, pricing and score →

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Last updated 7 Oct 2026 · How we research and update