Every built-in TypeScript utility type with its signature, plain-English description, a runnable example, and an interactive expansion against your own input type. Click a utility on the left to see how it transforms a sample User, override the input to see the expanded result for your own shape, and copy the snippet straight into a .ts file.
A small in-browser expander walks the input type and applies the selected utility — covers the common cases for Partial, Required, Readonly, Pick, Omit, Record, NonNullable, the string-case utilities, and unions for Exclude / Extract. For function- and promise-shaped utilities (ReturnType, Parameters, Awaited, …) only your real TypeScript compiler can resolve the inferred result — the snippet still pastes cleanly into a .ts playground.
Utility types are predefined generic type aliases in lib.es5.d.ts (and friends) that derive a new type from an existing one
using mapped, conditional, indexed-access, and template-literal features of the type system. The cheat sheet on the left covers all 21
types that ship with TypeScript 5.x. Hover an example in your IDE to see the canonical resolved form — the expander here covers
the structural cases (object shape transforms, union filtering, string-literal manipulation) so you can sanity-check the resulting shape
without leaving the browser.