Mock JSON Generator
Define a schema with field names and types and generate realistic fake JSON data in seconds. Runs in your browser.
Schema
// Click "Generate JSON" to see output here.About this tool
The Mock JSON Generator lets you define a custom schema by adding fields with names and data types, then instantly produce realistic-looking fake JSON records. Whether you need 5 records or 100, the tool builds them all client-side using your browser's built-in random number generator and a curated set of word lists and patterns.
Common use cases include testing REST APIs and GraphQL endpoints, seeding local databases during development, populating Postman or Insomnia collections with varied request bodies, and creating demo datasets for presentations or screenshots without exposing real user data.
The generator supports over 20 field types: plain strings, integers, floats, booleans, emails, UUIDs, ISO dates, unix timestamps, first and last names, full names, usernames, phone numbers, URLs, IP addresses, hex colour codes, lorem ipsum sentences and paragraphs, sequential array indexes, and custom literal values you type yourself.
Tips for best results: use the "Load example" button to see a working schema, then customise it to match your own data model. The "Custom value" type is handy for injecting a constant into every record - for example a static role or status field. Record counts up to 100 are supported; for larger datasets, generate multiple batches and merge them.
Because everything runs in the browser, your schema definitions and any generated data are never transmitted anywhere. Close the tab and everything is gone - no logs, no history, no tracking.
