Liquid Haskell is a refinement type checker for Haskell programs.

HLint is a tool for suggesting possible improvements to Haskell code.

A tool for detecting dead exports or package imports in Haskell code.

Haskell source code formatter

Stan is a command-line tool for analysing Haskell projects and outputting discovered vulnerabilities in a helpful way with possible solutions for detected problems.

Code health metrics from the terminal. Grades a project from A++ to F-- on cognitive complexity, duplication, indentation, Halstead effort and file size, and lists the files to look at first. Separate commands report cyclomatic and cognitive complexity per function, duplicates, code smells and the Maintainability Index. From git history it finds hotspots, code ownership and temporal coupling, and measures which files a diff reaches. A CI gate fails when a changed file gets worse.

Facebook's tools for code analysis, visualizations, or style-preserving source transformation for many languages.