Can I define custom schemas?

Yes. Specify field names and types: string, number, boolean, date, email, name, etc. Set constraints like min/max for numbers, format for dates, or provide explicit value lists.

How do I generate nested objects and arrays?

Define nested schemas within your schema. For arrays, specify the item schema and count (fixed or random range). Example: users with orders array, each order with items array.

Can I generate consistent related data?

Some generators support relations: order.userId references a user.id. For complex relations, generate in steps or use dedicated mock data libraries like Faker.js or MSW.

Random JSON Generator

Guide & TutorialOffline

Generate random JSON data with customizable depth and structure

Max Depth

Nesting level (1-10)

Properties

Root properties (1-20)

Array Size

Max array items (1-20)

About Random JSON Generator

Random JSON generator creates sample JSON data structures with realistic fake content. Generate users, products, addresses, or custom schemas with random but plausible values. Essential for API mocking, testing, UI development, and database seeding.

How It Works

Select a data type template (user, product, address) or define a custom schema. The generator fills each field with appropriate random values: names from name lists, emails from patterns, numbers within ranges, dates within spans. Output is valid JSON ready for use.

Technical Details

Uses faker-style data generation: realistic names, email patterns, address formats, phone numbers. Arrays can have variable lengths. Nested objects supported. Custom schemas define field types and constraints. Output is deterministic with optional seeding for reproducible results.

Common Use Cases

API Mocking

Create fake API responses during frontend development.

GET /users returns array of random user objects

Database Seeding

Populate development/test databases with sample data.

UI Testing

Test list rendering with variable-length random data.

Load Testing

Generate large volumes of realistic request payloads.

Code Examples

Random JSON Generator

javascript

// Simple random user generator
function randomUser() {
  const firstNames = ['John', 'Jane', 'Alex', 'Sam', 'Chris'];
  const lastNames = ['Smith', 'Johnson', 'Williams', 'Brown'];
  const domains = ['gmail.com', 'yahoo.com', 'outlook.com'];

  const firstName = firstNames[Math.floor(Math.random() * firstNames.length)];
  const lastName = lastNames[Math.floor(Math.random() * lastNames.length)];

  return {
    id: crypto.randomUUID(),
    firstName,
    lastName,
    email: `${firstName.toLowerCase()}.${lastName.toLowerCase()}@${domains[Math.floor(Math.random() * domains.length)]}`,
    age: Math.floor(Math.random() * 50) + 18,
    isActive: Math.random() > 0.3,
    createdAt: new Date(Date.now() - Math.random() * 365 * 24 * 60 * 60 * 1000).toISOString()
  };
}

// Generate array
const users = Array.from({ length: 10 }, randomUser);
console.log(JSON.stringify(users, null, 2));

Combine random selections from realistic value pools. Use UUID for IDs, calculated emails, constrained ages.

Tips & Best Practices

Use realistic value pools for plausibility
UUID for unique identifiers
Constrain numbers to valid ranges
Use Faker.js for more comprehensive fake data
Seed RNG for reproducible test data

Common Mistakes to Avoid

Using generated data in production
Unrealistic value combinations
Not handling relationship consistency
Generating more data than needed (slow)

When to Use This Tool

Use random JSON generator for API mocking, test database seeding, UI development with sample data, and load testing. Not for production data.

Frequently Asked Questions

Depends on the template. Names come from common name lists, emails follow standard patterns, addresses use real city/state combinations. Not suitable for production or user-facing content, but realistic enough for testing.

// Simple random user generator function randomUser() { const firstNames = ['John', 'Jane', 'Alex', 'Sam', 'Chris']; const lastNames = ['Smith', 'Johnson', 'Williams', 'Brown']; const domains = ['gmail.com', 'yahoo.com', 'outlook.com']; const firstName = firstNames[Math.floor(Math.random() * firstNames.length)]; const lastName = lastNames[Math.floor(Math.random() * lastNames.length)]; return { id: crypto.randomUUID(), firstName, lastName, email: `${firstName.toLowerCase()}.${lastName.toLowerCase()}@${domains[Math.floor(Math.random() * domains.length)]}`, age: Math.floor(Math.random() * 50) + 18, isActive: Math.random() > 0.3, createdAt: new Date(Date.now() - Math.random() * 365 * 24 * 60 * 60 * 1000).toISOString() }; } // Generate array const users = Array.from({ length: 10 }, randomUser); console.log(JSON.stringify(users, null, 2));