ArkType Has a Free API — TypeScript's Fastest Runtime Validator

ArkType is a runtime type validation library that uses TypeScript syntax directly. Write types once, validate at runtime — with the best error messages in the ecosystem.

Why ArkType?

Unlike Zod or Yup, ArkType lets you write validators using actual TypeScript-like syntax. No method chains, no special DSL — just types.

Quick Start

npm install arktype

import { type } from 'arktype';

const user = type({
  name: 'string',
  email: 'string.email',
  age: 'number > 0',
});

// Validate data
const result = user({ name: 'Alice', email: '[e-mail]', age: 30 });
if (result instanceof type.errors) {
  console.log(result.summary);
} else {
  console.log(result); // typed as { name: string, email: string, age: number }
}

Advanced Types

// Union types
const status = type('"active" | "inactive" | "pending"');

// Array types
const tags = type('string[]');

// Tuple types
const point = type(['number', 'number', 'number']);

// Optional properties
const config = type({
  host: 'string',
  port: 'number = 3000', // default value
  'debug?': 'boolean',
});

Morphs (Transform + Validate)

const parseDate = type('string').pipe((s) => new Date(s));
const parseInt = type('string').pipe((s, ctx) => {
  const n = Number(s);
  if (isNaN(n)) return ctx.error('a numeric string');
  return n;
});

const formData = type({
  name: 'string',
  age: type('string').pipe(s => Number(s)),
  joined: type('string').pipe(s => new Date(s)),
});

Scopes for Complex Schemas

import { scope } from 'arktype';

const $ = scope({
  user: {
    name: 'string',
    email: 'string.email',
    posts: 'post[]',
  },
  post: {
    title: 'string',
    body: 'string',
    author: 'user',
  },
});

const types = $.export();
const User = types.user;

Performance

ArkType is up to 100x faster than Zod for complex schemas. It compiles validators at definition time, not at validation time.

Library	Simple Object	Complex Nested
ArkType	1x (fastest)	1x (fastest)
Zod	10-20x slower	50-100x slower
TypeBox	2-5x slower	5-10x slower

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Are you using ArkType or still on Zod? Share your experience below!