schema-faker

Generate fake data from Zod schemas in a deterministic, type-safe, and extensible way.

schema-faker creates realistic-looking mock data directly from your existing schemas, without writing manual mocks.

Why schema-faker?

Most fake data libraries generate random values field-by-field.
schema-faker works schema-first.

Benefits

• ✅ Uses schemas you already have (Zod)
• ✅ Deterministic output (seed support)
• ✅ Fully type-safe
• ✅ No dependency on Faker
• ✅ Perfect for tests, seeds, and mock APIs

Type Support

• ✅ string
• ✅ number
• ✅ boolean
• ✅ object
• ✅ array
• ✅ optional
• ✅ enum
• ✅ nullable
• ✅ tuple
• ✅ union
• ✅ literal
• ✅ date
• ✅ record

Install

npm install schema-faker zod

Basic Usage

import { z } from "zod";
import { generate } from "schema-faker";

const User = z.object({
  id: z.string().uuid(),
  email: z.string().email(),
  age: z.number().min(18)
});

const user = generate(User);

// you can also create multi objects

const users = generate(User, {
  count: 5,
  seed: 42,
});

Override Data Usage

import { z } from "zod";
import { generate } from "schema-faker";

const UserSchema = z.object({
  id: z.string().uuid(),
  email: z.string().email(),
  age: z.number().min(18).max(65),
  isActive: z.boolean(),
});

// email and age will stay the same
const user = generate(UserSchema, {
  overrides: {
    email: "[email protected]",
    age: 30,
  },
});

console.log(user);

Strict mode

By default, unsupported Zod types are ignored. Enable strict mode to throw an error instead:

generate(schema, { strict: true });