JSON Mock Data Generator

Generate Realistic Test Data Instantly

Testing with real user data is risky. Privacy concerns, data leaks, compliance issues. But testing with obviously fake data—"Test User 1", "test@test.com"—doesn't catch edge cases. You need data that looks real without being real.

This generator uses faker.js to create realistic test data at scale. Names, emails, addresses, phone numbers, job titles, dates—all random but believable. Define your JSON structure with placeholders, pick how many records you need, and generate hundreds of rows in seconds. Perfect for API testing, database seeding, or UI prototypes.

Why Use a Mock Data Generator?

• Rapid Prototyping - Get sample data immediately without writing generation scripts
• Testing at Scale - Create up to 1,000 records instantly for load testing scenarios
• Realistic Data - Faker-powered values mimic real user data patterns accurately
• Custom Templates - Build exactly the structure you need with nested objects and arrays
• No Backend Required - Runs entirely in your browser, no server infrastructure needed

How to Use Template Placeholders

1. Define Your Structure - Write a JSON template matching your API or database schema
2. Add Placeholders - Replace values with {{placeholder}} syntax
3. Set Record Count - Choose between 1 and 1,000 records for your dataset
4. Generate - Click the button and watch realistic data appear instantly
5. Export - Copy to clipboard for immediate use or download as a JSON file

Common Use Cases

• API Testing - Generate mock request/response data for testing REST endpoints
• Database Seeding - Create initial data for development and staging databases
• UI Prototypes - Populate interfaces with realistic data for client demos
• Load Testing - Build large datasets to stress-test application performance
• Documentation - Create realistic examples for API docs and integration guides

Supported Data Types

Over 50 placeholder types available: personal info (names, emails, phones), geographic data (addresses, cities, countries), business data (company names, job titles), temporal data (dates, timestamps), financial data (amounts, currencies), text content (lorem ipsum, paragraphs), technical data (UUIDs, IP addresses), and basic types (numbers, booleans). Click "Placeholders" above for the complete list.

Frequently Asked Questions

Can I use nested objects and arrays in templates?

Absolutely. The parser handles arbitrary nesting depth. Create complex hierarchies with objects inside arrays inside objects. Placeholders work at any level. The generator maintains your structure while replacing every placeholder with random values.

How many records can I generate at once?

Between 1 and 1,000 per batch. Need more? Generate multiple batches and combine them. For truly massive datasets (tens of thousands of records), consider using faker.js directly in a script rather than a browser tool. Browser memory has limits.

Is the generated data truly random?

Yes, every generation produces new pseudo-random values via faker.js. Hit generate twice with the same template and you'll get completely different data. The randomness is good enough for testing but not cryptographically secure. Don't use this for generating passwords or security tokens.

Can I use the same placeholder multiple times?

Sure. Each occurrence generates independently. Using {{name}} in three different fields produces three different random names. If you want the same value repeated, you'd need to handle that post-generation. This tool focuses on variety, not consistency within a record.

What happens if I use an unsupported placeholder?

The validator catches it before generation and shows an error. You'll see exactly which placeholders aren't recognized. Check the "Placeholders" reference for the full list of supported types. Typos are the most common issue—{{emai}} instead of{{email}}. The error message helps you spot these quickly.