JSON Generator: create mock & fake JSON data online

What is a JSON generator?

A JSON generator (or mock-data generator) turns one sample record into as many realistic, randomized records as you need. Instead of hand-writing test data, you paste a single object that shows the shape you want, pick a count, and get a JSON array back. It's ideal for seeding databases, mocking API responses, load-testing, and filling prototypes with believable placeholder data. Everything runs in your browser, so your schema and the generated data stay on your machine.

Type- and key-aware values

Numbers stay numbers; integers stay integers, decimals stay decimals.
Strings are chosen by key: emails, UUIDs, ISO dates, names, URLs, phone numbers, and colors are detected from the field name.
Booleans flip randomly; nested objects and arrays keep their structure, with arrays getting a few generated elements.

How to use

Paste one sample JSON record into the Template pane (or load the sample).
Set how many records you want with Count (1 to 1000).
Click Generate. You get an array of records with the same shape but randomized values.
Values are chosen by type and key: email fields get emails, id/uuid get UUIDs, dates get ISO timestamps, names get names.
Click Regenerate for a fresh batch, then Copy or Download. Everything runs in your browser.

Examples

Sample record → mock array

Input

{ "id": 1, "name": "Ada", "email": "[email protected]" }

Output

[
  { "id": 734, "name": "Grace", "email": "[email protected]" },
  { "id": 88,  "name": "Linus", "email": "[email protected]" }
]

Nested objects and arrays are kept

Input

{ "user": { "name": "x" }, "tags": ["a"] }

Output

[
  { "user": { "name": "Katherine" }, "tags": ["cobalt", "atlas"] }
]

FAQ

How does the generator decide values?

It reads your sample and generates each field by its value type and its key name. Numbers stay numbers (integers stay integers), booleans flip randomly, and strings become realistic values: email keys get emails, id/uuid keys get UUIDs, date/createdAt keys get ISO timestamps, name keys get names, and others get short words.

How many records can I generate?

From 1 to 1000 per batch. That covers most seeding, fixture, and demo needs while keeping the output fast to render in the browser.

Is the data the same every time?

No. Each click re-rolls fresh random values from your template, so you can generate as many distinct batches as you like.

Does anything get uploaded?

No. Generation runs 100% in your browser, so your template and the generated data never leave your machine. Check DevTools: zero network requests.

What can I use the output for?

Seeding a database, mocking an API response, load-testing, filling a UI with placeholder data, or building test fixtures. Pair it with the JSON Schema generator or JSON to SQL to go further.

"JSON Generator":{ }