Fun Data Playground json export
Field types ← Generator

JSON test data generator

Design a schema and export a pretty-printed JSON array with proper types — numbers stay numbers, booleans stay booleans, blanks become null. Perfect for fixtures and mock APIs.

Generate JSON data → Browse field types

What the output looks like

[
  {
    "id": 1,
    "full_name": "Elena Rossi",
    "email": "elena.rossi7@example.org",
    "is_active": true,
    "last_login": null
  }
]

Why JSON?

JSON is the default interchange format of the web, and unlike CSV it keeps your types: integers and decimals are emitted as numbers, booleans as true/false, and fields with a Blank % produce genuine nulls. That makes the output drop-in ready for unit test fixtures, seed files, Storybook data and mock API responses.

Ideas for the output

  • Test fixtures — export with a seed (e.g. sprint-42) and commit the file; every regeneration is byte-identical.
  • Mock backends — serve the array from our sibling Fun API Playground or from json-server for an instant fake REST API.
  • Frontend development — import the file directly and build UI against realistic names, addresses and prices instead of foo/bar.

Quick recipe: data-driven tests

import users from './fixtures/fundata_100_rows.json';

for (const user of users.slice(0, 10)) {
  test(`signup works for ${user.email}`, async ({ page }) => { /* … */ });
}

Types, escaping and compatibility

The export is a valid UTF-8 JSON array. Numeric fields remain JSON numbers, Boolean fields remain booleans and blank values become null; strings are escaped with JSON.stringify-compatible rules. That makes one file usable from JavaScript, Python, Java, .NET and any standards-compliant parser. Choose NDJSON when a pipeline needs one independently parseable record per line.

Common JSON questions

Can I use this output as a mock API response?

Yes. Export a seeded JSON array and serve it from a fixture route, json-server or a test interceptor. See the mock API data guide for schema ideas.

Does JSON preserve nulls and number types?

Yes. Integer, decimal and Boolean fields are emitted as native JSON values, while a field selected by Blank % becomes null rather than an empty string.

Other formats

The same schema exports to all six formats — switch with one dropdown: CSV, TSV, NDJSON, SQL, XML. New here? Start with the getting-started guide or the full field type reference.