gvergnaud/ts-pattern

The exhaustive Pattern Matching library for TypeScript, with smart type inference.

mattpocock/ts-reset

A 'CSS reset' for TypeScript, improving types for common JavaScript API's

sindresorhus/type-fest

A collection of essential TypeScript types

sinclairzx81/typebox

Json Schema Type Builder with Static Type Resolution for TypeScript

ArkType

Typescript's 1:1 validator, optimized from editor to runtime

tsd

Check TypeScript type definitions

LuciNyan/ts-known

This library offers guards for common types, and methods to generate type guards for specific types quickly. Safely handle unpredictable unknown types with ease.