TFLint Terraform Linter

TFLint is a pluggable linting tool for Terraform that catches provider-specific errors and best practice violations. Created by Kazuma Watanabe in 2017 and now maintained by the terraform-linters organization, TFLint has over 5,400 stars as of 2026. Unlike Terraform's built-in validate command (which only checks syntax and internal consistency), TFLint performs deeper analysis including provider-specific validation, detecting impossible values, deprecated syntax, and policy violations before Terraform plan or apply runs. Key features include: provider-specific rules (analyzing Terraform configurations against actual cloud provider APIs to detect invalid instance types, non-existent regions, unsupported features, and deprecated resources for AWS, Azure, GCP, and other providers), syntax and format checking (verifying Terraform HCL syntax correctness and detecting formatting issues), best practice enforcement (identifying missing tags, hardcoded values that should be variables, unused declarations, and naming convention violations), rule customization (enabling, disabling, and configuring individual rules via .tflint.hcl configuration files), plugin architecture (extending TFLint with custom rules and provider-specific rule sets via TFLint Rulesets), module inspection (analyzing module sources, versions, and input variables for consistency), variable validation (checking that variable definitions have appropriate types, descriptions, and defaults), CI/CD integration (running TFLint in GitHub Actions, GitLab CI, and Jenkins with machine-readable JSON output), parallel execution (linting multiple files concurrently for faster results), and automatic fixing (automatically correcting some formatting and style issues).