A collection of essential TypeScript utility types that should have been built-in.
Type Fest is a curated collection of essential TypeScript utility types that address common gaps in the language's built-in type system. It provides developers with reliable, well-tested type helpers for tasks like deep object transformations, conditional type logic, string manipulation, and JSON handling—many of which the maintainer believes should have been included in TypeScript itself.
TypeScript developers building complex type-safe applications, library authors needing robust type utilities, and teams wanting to enforce stricter type contracts and improve developer experience through better type hints.
Developers choose Type Fest for its comprehensive, production-ready utility types that are meticulously maintained, follow TypeScript's design principles, and solve real-world type system pain points without introducing experimental or niche features.
A collection of essential TypeScript types
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Provides recursive utilities like PartialDeep and ReadonlyDeep for modifying nested structures, which TypeScript's built-in types lack, as highlighted in the Key Features.
Offers enhanced versions such as Except (a stricter Omit) and Writable for precise type manipulation, reducing potential runtime errors.
Includes a wide range of utilities for JSON serialization, string operations, array manipulation, and more, filling common gaps in TypeScript's type system.
Well-maintained with a focus on reliable, non-experimental types, clear contributing guidelines, and sponsorship support, ensuring long-term viability.
Requires TypeScript >=5.9, ESM, and strict mode in tsconfig, which excludes legacy projects or those with different configurations.
With over 100 utility types, developers may face decision fatigue or import unnecessary types, complicating codebase maintenance.
Purely compile-time focused; for runtime needs, separate packages like ts-extras are required, adding to the dependency ecosystem.