JSON Mock Data Generator
Generate realistic fake JSON data from a template. Smart field detection turns key names into realistic values. Free, client-side, no signup.
Supported field names
How to Use
- Paste a JSON object as a template. The key names and value types tell the generator what kind of data to produce.
- Choose how many records to generate (1–100).
- Click Generate Mock Data to create realistic fake data.
- Adjust the seed for different but reproducible output. Click Randomize for fresh data.
Smart Field Detection
The generator automatically recognizes common field names and produces appropriate data. A key named "email" generates realistic email addresses like emma.garcia@gmail.com. A key named "address" produces street addresses. This works for dozens of field names across categories like identity, location, content, dates, and more.
Common Use Cases
- Frontend prototyping — populate UI components with realistic data during development
- Unit testing — generate test fixtures that look like production data
- API mocking — create mock API responses for development and testing
- Database seeding — generate seed data for local development databases
- Demo environments — fill staging apps with believable sample data
- Documentation — create realistic JSON examples for API docs
Reproducible Output with Seeds
Unlike truly random generators, this tool uses a seeded pseudo-random number generator. The same seed + template always produces the same output. This is useful for tests that need deterministic data, sharing examples with teammates, and creating consistent demo environments.
Nested Objects and Arrays
The generator handles nested structures. If your template contains an address object with street, city, and state fields, each will be populated with appropriate data. Arrays in the template are expanded to 1–5 items, each individually generated.
Mock Data in Code
For programmatic mock data generation, libraries like Faker.js (JavaScript), Faker (Python), and go-faker (Go) are popular choices. They offer fine-grained control over locales, custom providers, and seeding. This tool is ideal when you need quick mock data without installing dependencies or writing code.
Related Tools
Validate your generated data with the JSON Validator. Format it with the JSON Formatter. Convert to CSV with the JSON to CSV Converter. Generate TypeScript types from your mock data with JSON to TypeScript. Query the output with the jq Playground.
Frequently Asked Questions
- How does the mock data generator work?
- Paste a JSON object as a template. The generator reads each key name and value type, then produces realistic fake data based on the key name. For example, a key called "email" generates realistic email addresses, "name" produces full names, and "age" generates numbers in a reasonable range.
- What field names are recognized?
- The generator recognizes dozens of common field names including: name, firstName, lastName, email, phone, address, city, state, zipCode, country, company, title, description, url, image, avatar, color, ip, date, createdAt, updatedAt, id, uuid, age, price, rating, count, password, token, tag, category, role, status, and many more.
- Can I generate reproducible data?
- Yes. The generator uses a seeded random number generator. As long as you use the same seed and the same template, you will get identical output every time. Change the seed to get different but equally realistic data.
- Is my data safe?
- Yes. All data generation happens entirely in your browser using JavaScript. No data is sent to any server. Your JSON template never leaves your machine.
- How is this different from Mockaroo or JSON Generator?
- Unlike Mockaroo, CodeTidy's mock data generator requires no account, runs 100% client-side, and automatically infers the right data type from your key names. Just paste a real JSON object and get instant mock data — no schema configuration needed.
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