Generate fake JSON records for development and testing with toggleable fields and a reproducible seed. Runs entirely in your browser.
Generation happens locally in your browser. No dataset ever leaves your device.
Set a seed above 0 and the same value always reproduces the same dataset; leave it empty for Math.random.
Every control is wired to a single rebuild function with a 250 ms debounce: change the count, toggle a field or type a seed and the dataset regenerates live. Each record is built by walking the fixed field list in schema order — id, name, email, username, phone, address, date, company, product, sentence, price, active, uuid — and keeping only the checked fields, so the key order inside every object stays stable and predictable. The result is pretty-printed with two-space indentation.
No — and that is the point. Every address ends in example.com, example.org or example.net, the three domains RFC 2606 reserves for documentation and testing, so they can never reach a real inbox. Phone numbers use the 555 exchange reserved for fictional use. The data is safe to commit and safe to test with, but it is not usable for signing up anywhere.
Leave the seed empty and the tool uses Math.random, so every keystroke produces fresh data. Enter a whole number from 1 upward and the tool switches to a small built-in mulberry32 pseudo-random generator initialized with that seed: the same seed plus the same settings reproduces a byte-for-byte identical dataset, on any machine, in any session. One exception: the uuid field always comes from the Web Crypto API and is not reproducible by seed.
A 1,000-record pretty-printed JSON blob is large enough to make the textarea sluggish, so the visible preview is capped at the first 100 records. Copy JSON and Download .json always serialize every record you asked for — the cap is display-only.
No. The generator offers a fixed schema of thirteen field types (id, name, email, username, phone, address, date, company, product, sentence, price, active, uuid) and you toggle which ones appear. Keeping the vocabulary fixed is what makes the output predictable, the seeding meaningful and the page dependency-free.
No. The whole generator is vanilla JavaScript running in your browser — no CDN, no API, no network request. The dataset is built and stays in your tab, and closing the page discards it.
If you just finished with Mock JSON Data Generator, the natural next steps are Word & Character Counter, Unique Word Counter, Text Case Converter, or browse every tool in Daily Tools.