samchon/typia

★ 5,783TypeScriptAudience · developerComplexity · 3/5LicenseSetup · moderate

Mindmap

mindmap
  root((Typia))
    What it does
      Auto generate validators
      TypeScript types as source
      No schema files needed
    Core Features
      Runtime type checks
      JSON parse and validate
      Random data generator
    AI Support
      LLM function calling
      Schema generation
      Typed tool definitions
    Setup
      Vite plugin
      Webpack plugin
      Next.js integration

mindmap root((Typia)) What it does Auto generate validators TypeScript types as source No schema files needed Core Features Runtime type checks JSON parse and validate Random data generator AI Support LLM function calling Schema generation Typed tool definitions Setup Vite plugin Webpack plugin Next.js integration

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Things people build with this

USE CASE 1

Validate incoming API request bodies against your TypeScript types without maintaining a separate JSON Schema file.

USE CASE 2

Parse and validate JSON from external sources so bad data is caught before it reaches your application logic.

USE CASE 3

Generate random test data that matches your TypeScript types for unit and integration testing.

USE CASE 4

Produce the function-calling schemas needed for an AI model to call your TypeScript functions directly.

Tech stack

TypeScriptViteNext.jsWebpackNode.js

Getting it running

Difficulty · moderate Time to first run · 30min

Requires a custom compiler step via a bundler plugin (Vite, Webpack, or ts-patch), the standard tsc command alone is not enough.

Use freely for any purpose including commercial projects under the MIT license, keeping the copyright notice.

In plain English

Typia is a TypeScript library that converts your existing type definitions into real, working runtime checks, without requiring any extra schema definitions or configuration files. Standard TypeScript checks types only during development, meaning bad data can slip through when actual values arrive from a network request or file. Typia closes that gap by reading your TypeScript types at compile time and generating the actual checking functions automatically. The central mechanic is what the project calls transformation. When you call a Typia function like typia.is(), the compiler replaces that call with a generated type-checking function tailored exactly to your type. You write one line. You do not maintain separate schema files, and you do not write validators by hand. The plain TypeScript type is the single source of truth. Typia covers several areas beyond basic type checks. It provides JSON parsing and serialization functions that validate data as they convert it, so bad input is caught before it reaches the rest of your application. It supports Protocol Buffers, a compact binary format used in performance-sensitive systems for network communication. A random data generator creates values that match your types, which is useful for testing. There is also a module for LLM function-calling setup, where Typia generates the schemas and validators needed for an AI model to call your code functions directly. The README includes speed comparisons from benchmarks: the runtime validators are described as 20,000 times faster than a library called class-validator, and the JSON serialization is described as 200 times faster than class-transformer. Typia requires a custom compilation step. You need to use specific toolchain wrappers rather than the standard TypeScript compiler. Bundler integration with Vite, Next.js, Webpack, and others is available through a plugin. The project is MIT licensed. An online playground at typia.io/playground lets you test how the transformation works before you set anything up locally.

Copy-paste prompts

Prompt 1

Using typia, add runtime validation to my Express route handler so that POST request bodies are checked against my TypeScript User type and invalid requests return a 400 error.

Prompt 2

Show me how to use typia.json.assertParse to safely parse an API response and throw a typed error if the shape does not match my interface.

Prompt 3

Set up typia with Vite so the type transformation runs at build time in my React project.

Prompt 4

Use typia's random data generator to create 100 sample objects matching my Product type for use in a Jest test suite.

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