The Terraform fmt Checker pastes your Terraform configuration and shows whether terraform fmt would reformat it, together with the normalized output. It is a private, client-side approximation of terraform fmt that parses your HCL and re-emits it with canonical formatting, then tells you if the file would change.
The checker normalizes layout: two-space indentation, a space around the equals sign, and consistent block structure. It does not implement every nuance of the Go formatter that ships with Terraform, but it is close enough to preview formatting issues during a review or when you cannot run Terraform locally. Nothing is written to disk and nothing is uploaded; the result is displayed and can be copied, downloaded as a .tf file, or printed. It is a fast way to keep a pull request tidy and to teach the canonical HCL style.
The tool is particularly handy in code review. Instead of installing Terraform to verify a contributor formatting, a reviewer can paste the diff into the checker and immediately see whether fmt would touch it. That keeps review comments focused on logic rather than whitespace, and it reduces the number of CI failures caused by a forgotten terraform fmt. It also helps new contributors learn what canonical HCL looks like before they ever run the command.
Because the checker is an approximation, treat a YES result as a strong hint rather than a guarantee. For an authoritative answer in automation, run terraform fmt -check in your pipeline; use this tool for fast, local, pre-commit feedback when Terraform is not installed or when you want a quick second opinion on a snippet.