ArkType Has a Free API — Here's How to Validate Data with TypeScript's Type Syntax

ArkType is a runtime type validation library that uses TypeScript's own type syntax. It is the fastest validator in the ecosystem and produces 1:1 TypeScript types from your definitions.

Installation

npm install arktype

Basic Types

import { type } from "arktype";

// Define types using TS syntax
const user = type({
  name: "string",
  email: "string.email",
  age: "number.integer >= 0",
  role: "admin | user | moderator"
});

// Validate data
const result = user({ name: "Alex", email: "[e-mail]", age: 28, role: "admin" });

if (result instanceof type.errors) {
  console.log(result.summary); // Human-readable errors
} else {
  console.log(result.name); // Fully typed!
}

Advanced Types

// Arrays and tuples
const tags = type("string[]");
const pair = type(["string", "number"]);

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

// Unions and intersections
const response = type({
  status: "success | error",
  data: "string | number | null"
});

// Morphs (transform on validate)
const stringToNumber = type("string").pipe(s => parseInt(s, 10));
const result = stringToNumber("42"); // 42 (number)

Nested Objects

const address = type({
  street: "string",
  city: "string",
  zip: "/^\\d{5}$/"
});

const company = type({
  name: "string",
  address: address,
  employees: "number.integer > 0",
  founded: "string.date.iso"
});

Pattern Validation

// Regex patterns
const slug = type("/^[a-z0-9-]+$/");
const uuid = type("string.uuid");
const url = type("string.url");

// Numeric constraints
const percentage = type("number >= 0 <= 100");
const positiveInt = type("number.integer > 0");

Why ArkType?

• Fastest validator — benchmarks show 100x faster than Zod for complex schemas
• TS syntax — no new API to learn, just write TypeScript types
• 1:1 type inference — extracted types match your runtime validators exactly
• Tiny bundle — ~5KB gzipped

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