TypeNarrow

Suggest tighter TypeScript types by analyzing runtime value patterns

Code & DevelopmentFreemium

TypeNarrow analyzes TypeScript codebases to find overly broad types like any, unknown, string, and number that could be narrowed to literal types, branded types, or discriminated unions based on actual usage patterns. The tool traces value flows through functions to determine the tightest possible type at each point and generates codemods to apply the refinements. Teams use it to incrementally improve type safety in codebases that started with loose typing.

Key Features

• ✓Broad type detection
• ✓Value flow tracing
• ✓Codemod generation
• ✓Literal type suggestions
• ✓Discriminated union refactoring