Type inference utilities

type-fest is a library of reusable utility types for performing complex transformations and validations on objects, arrays, strings, and numeric ranges in TypeScript. It provides a collection of type definitions designed to handle advanced structural changes and constraints. The project distinguishes itself by offering specialized logic for string literal processing, such as casing transformations and pattern-based modifications, and type-level arithmetic for calculating numeric ranges and absolute values. It also includes utilities for enforcing deep immutability, ensuring union mutual exclu

Hotscript is a comprehensive suite of composable utilities designed for performing structural transformations and mathematical operations within the TypeScript type system. It serves as a type-level manipulation library that provides a set of higher-order functions to map, filter, and reduce the structure of type definitions. The project focuses on type-level programming by implementing reusable logic and calculations directly within types. This includes the ability to create custom type functions, implement type-level pattern matching, and compose sequences of transformations where each oper

This is a TypeScript utility type library providing advanced type aliases and mapped types for complex object and union transformations. It implements specialized tools for creating branded nominal types, extracting type metadata, and performing set operations on union types. The project distinguishes itself through a toolkit for recursive object transformations, allowing for the application of property constraints like read-only or optional status across deeply nested structures. It also provides a system for computing intersections, differences, and complements between union types to simula

TypeScript is a language that extends standard syntax by adding a static type system. It identifies potential runtime errors by analyzing the behaviors and capabilities of values during the compilation process. The language supports object-oriented structures, including classes with inheritance and member visibility control, as well as flexible function definitions that utilize generics, overloads, and parameter destructuring. The project provides a compiler that manages the build lifecycle through a command-line interface, offering configurable options for module resolution, code generation,

ts-toolbelt is a collection of specialized utilities for manipulating and validating TypeScript types. It provides a toolkit for performing complex transformations on objects, unions, and functions to enforce strict data consistency at compile time. The library features dedicated transformers for function types, including utilities for currying, composition, and signature extraction. It also includes an object type manipulator for deep merging, patching, and reshaping complex structures. The capability surface extends to literal string processing, type-level arithmetic, and tuple operations.

ts-reset is a TypeScript type enhancement library that overrides and augments the built-in type definitions for standard JavaScript APIs. Its core purpose is to replace unsafe any return types with stricter alternatives like unknown, forcing developers to explicitly validate data before using it. The library achieves this through global type augmentation and declaration merging, applying changes across the entire project without requiring per-file imports. The library differentiates itself by targeting specific pain points in everyday TypeScript usage. It relaxes type constraints on array

Zod is a TypeScript-first schema declaration and validation library designed to ensure end-to-end data integrity. It functions as a runtime type guard, allowing developers to define complex data structures through a declarative, chainable syntax. By using these schema definitions, the library automatically derives static TypeScript types, eliminating the need for manual type duplication and ensuring that runtime data matches expected application contracts. The library distinguishes itself through functional schema composition, which enables the creation of hierarchical structures by nesting a

Valibot is a modular, type-safe schema library for validating and parsing structural data in TypeScript environments.

Arktype is a TypeScript runtime validation library and schema orchestrator. It synchronizes TypeScript types with runtime data validation, allowing users to define type-safe schemas that ensure unknown data adheres to specific structures during application execution. The project distinguishes itself by using set-theory type analysis to determine intersections and subtype compatibility, alongside JIT-compiled validation functions for optimized performance. It supports advanced type modeling through branded type constraints, recursive alias resolution, and the ability to generate runtime valida

io-ts is a TypeScript runtime validation library that provides a composable codec system for decoding and encoding data at the boundaries of an application. It defines data schemas using structural types, where the shape of data determines its validity rather than nominal names, and produces runtime type guards from those definitions for efficient validation checks. The library is built around bidirectional codec mappings that combine decoding, encoding, and type checking into single reusable units. It supports a composable decoder pipeline where small validation steps can be chained together

Meta-typing is a TypeScript metaprogramming toolkit that executes complex algorithms, mathematical operations, and data structure traversals entirely within compile-time type definitions. It functions as a type-level computation engine that evaluates numeric expressions, basic arithmetic, and aggregate calculations through recursive type evaluation and tuple-based data representations during the compilation phase. The library implements a comprehensive collection of advanced algorithms and data structures, including collection manipulation utilities for array slicing, filtering, merging, and