Random JSON Array Generator

Generates a random JSON array of a chosen length and item type (number, string, boolean, or mixed) for use as sample data, test fixtures, or placeholder API responses. A free online tool from Staaarter, right in your browser.

Runs locallyUpdated 2026-07-24

Overview

Introduction

Testing a function that processes a JSON array, or mocking an API response, usually means writing out a handful of plausible array items by hand. This generator produces that array instantly, with a chosen length and item type.

It's a quick way to get throwaway sample data without needing it to mean anything in particular.

What Is Random JSON Array Generator?

A generator that produces a flat JSON array (no nested objects or arrays) of a chosen length, filled with random numbers, strings, booleans, or a mix of all three.

Every item is a plain scalar value, so the output is always valid, immediately parseable JSON with no structure beyond the array itself.

How Random JSON Array Generator Works

For each position in the array, the tool picks a value according to the selected item type: a random integer between 0 and 1000, a random word from a small sample bank, a random boolean, or (in mixed mode) a randomly chosen one of the three per item.

The resulting array is serialized with JSON.stringify and two-space indentation, ready to copy or download directly.

When To Use Random JSON Array Generator

Use it when you need quick placeholder data for a function signature, a UI component, or an API mock that expects an array of scalars.

It's also handy for generating a small test fixture without having to think up realistic-looking values yourself.

Features

Advantages

  • Produces valid JSON instantly with no setup.
  • Supports number, string, boolean, and mixed item types.
  • Regenerates instantly when you change the length or type, so you can browse several samples quickly.

Limitations

  • The string word bank is small and fixed, so values will repeat in longer arrays.
  • There's no way to generate nested objects or arrays as items; every item is a flat scalar.

Examples

Mixed array of 5 items

Input

length: 5, itemType: mixed

Output

[
  482,
  "admin",
  true,
  "Ada Lovelace",
  17
]

Each item independently rolls between a number, string, and boolean.

Best Practices & Notes

Best Practices

  • Use "number" or "boolean" item type when testing a function that expects a specific scalar type throughout the array.
  • Regenerate a few times if the first sample happens to look too uniform for your test case.
  • Keep the array length small (5-10) for quickly eyeballed test fixtures; use a larger length only when you specifically need volume.

Developer Notes

The mixed item type rolls a fresh type per item rather than picking one type for the whole array, which better resembles how real-world untyped JSON arrays (e.g. from a loosely-typed API) tend to mix scalar types rather than being internally consistent.

Random JSON Array Generator Use Cases

  • Generating placeholder data for a UI component that renders a list
  • Creating a quick test fixture for array-processing code
  • Mocking an API response body during frontend development

Common Mistakes

  • Expecting the generated strings to be unique; the word bank is small and intentionally reused.
  • Requesting nested objects as items; this tool only produces flat scalar items.

Tips

  • Need an array of objects instead of scalars? Fakeson Generator can produce that from a template.
  • Use Randomize JSON Array afterward if you want to reshuffle the same generated array's order.

References

Frequently Asked Questions