BYTETOOLS

Mock JSON Data Generator

Generate fake JSON, NDJSON or CSV test data online. Define fields — names, emails, UUIDs, dates, numbers, enums — and create up to 5000 records.

What is the Mock JSON Data Generator?

The ByteTools Mock JSON Data Generator creates realistic fake records from a field list you define. Pick a type for each field — full name, email, UUID v4, integer range, date range, boolean, enum, lorem text, phone number or city — set how many records you need, and export the result as a JSON array, NDJSON lines or CSV.

  • 10 field types: name, email, UUID, integer, date, boolean, enum, lorem, phone, city
  • Configurable ranges for integers and dates, custom enum values
  • Export as JSON array, NDJSON or CSV with proper quoting
  • Up to 5000 records per run, generated instantly
  • Safe fake data: example.com emails and 555-01XX phone numbers
  • 100% offline and private — nothing leaves your browser

How to use the Mock JSON Data Generator

  1. 1

    Define your fields: give each a name, a type and options where needed (like 1,100 for an integer range).

  2. 2

    Add or remove fields until the record shape matches your schema.

  3. 3

    Set the number of records (up to 5000) and pick JSON, NDJSON or CSV.

  4. 4

    Click Generate, then copy the data or download the file.

About the Mock JSON Data Generator

The ByteTools Mock JSON Data Generator creates realistic fake records from a field list you define. Pick a type for each field — full name, email, UUID v4, integer range, date range, boolean, enum, lorem text, phone number or city — set how many records you need, and export the result as a JSON array, NDJSON lines or CSV.

It is built for developers and testers seeding databases, mocking API responses, filling UI prototypes and writing fixtures. Randomness comes from crypto.getRandomValues, emails use reserved example.com-style domains and phone numbers use the fictional 555-01XX range, so generated data can never collide with real people.

Generation is fully offline — no faker library, no API, no account. Everything runs 100% locally in your browser and nothing is uploaded or stored, so your schema stays private.

Frequently asked questions

How do I generate fake JSON data for testing?

Add a field for each property you need, choose its type, set the record count and click Generate. You get a JSON array of unique random records that you can copy into fixtures or download as a file.

What is NDJSON and when should I use it?

NDJSON is newline-delimited JSON — one complete object per line. It is the standard input format for streaming pipelines and bulk-import endpoints like Elasticsearch, so choose it when your target reads records line by line.

How do I set a range for numbers or dates?

Type the range into the field's options box: 1,100 gives integers from 1 to 100, and 2024-01-01,2024-12-31 gives dates inside 2024. Enums take a comma-separated list of values and lorem takes a word count.

Is the generated data safe to use publicly?

Yes by design. Emails end in example.com, example.org or example.net (reserved for documentation), and phone numbers use the 555-01XX block reserved for fiction, so no real person or mailbox can be contacted by accident.

Why is there a 5000 record limit?

Everything is generated in your browser tab, and 5000 keeps the page instant even with many fields. If you need more, generate several batches — each run produces fresh random values.

Does this tool call a faker API?

No. The word lists and generators are embedded in the page and randomness comes from your browser's crypto.getRandomValues, so it works offline and your schema is never sent anywhere.

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