TypeScript Utility Types Explorer
Browse built-in utility types with signatures, before/after examples, and mapped-type implementations. Use the chooser if you know the goal but not the type name.
Before (input)
After (result)
When to use
How it is implemented
About this tool
TypeScript ships ~20 built-in utility types for transforming object, union, function, and string shapes. Partial makes every field optional for update payloads. Pick and Omit carve subsets from large interfaces. ReturnType and Awaited peel types off functions and promises.
This explorer lists each type with its signature, before/after examples, and the mapped-type implementation TypeScript uses internally. Use the "I want to…" chooser when you know the goal but not the type name.
Results are precomputed static strings — no compiler in the browser. Share a specific type via the URL query param.
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