What are some type-level TypeScript libraries? [closed]

Answer 1

Some honorable mentions:

Types

• type-fest A collection of essential TypeScript types
• ts-essentials All basic TypeScript types in one place
• typescript-conditional-types Helpers for typescript generic types
• ts-types-utils Type utilities for typescript
• type-zoo A menagerie of useful type operators for TypeScript
• unionize Boilerplate-free functional sum types in TypeScript
• hkts A simple encoding of higher-kinded types in TypeScript
• safe-units Type-safe TypeScript units of measure
• type-plus Additional types and types adjusted utilities for TypeScript

Test own Types with Types

• is Type check values
• conditional-type-checks Types for testing TypeScript types.

Transformers

• ts-transformer-keys