Zod Has a Free TypeScript Schema Validation Library With Zero Dependencies

#zod #typescript #validation #opensource

Zod is a TypeScript-first schema declaration and validation library. Define a schema once — get runtime validation AND static TypeScript types.

What You Get for Free

TypeScript-first — types inferred from schemas
Zero dependencies — lightweight
Composable — build complex schemas from simple ones
Transforms — parse and transform data
Error messages — detailed, customizable errors
Works everywhere — Node, Deno, Bun, browsers

Define and Validate

import { z } from 'zod';

const UserSchema = z.object({
  name: z.string().min(2),
  email: z.string().email(),
  age: z.number().int().positive().optional(),
});

type User = z.infer<typeof UserSchema>;
// { name: string; email: string; age?: number }

const result = UserSchema.safeParse({ name: 'Alice', email: 'alice@example.com' });
if (result.success) console.log(result.data); // typed as User

API Validation (Express)

app.post('/api/users', (req, res) => {
  const result = UserSchema.safeParse(req.body);
  if (!result.success) return res.status(400).json(result.error);
  createUser(result.data); // data is typed!
});