Mock JSON Generator
Make realistic fake JSON from an example, or anonymise real JSON.
Paste an example, open a file, or press Load sample.
Think a result is wrong? Report it on GitHub
How do I generate fake JSON test data?
Generate realistic fake JSON test data from an example, or anonymise real JSON before sharing it. UK or US style data. Free; nothing leaves your browser.
Paste one real or typical record, or an array of them, and choose how many to make. Each field's kind is guessed from its name and value: email gets email addresses, postcode gets postcodes, a UUID gets UUIDs, a date gets dates in the same range. The Fields table shows every guess, and you can change any of them, including to Keep the example's value. With several example records, fields that only sometimes appear stay optional, numbers keep their range, and a field like status with a few repeated values picks from those values.
Can I get the same data again?
Yes. The data comes from a seed, shown above the example: the same example, settings and seed always give exactly the same records, which keeps test fixtures stable. New data picks a new seed.
How does anonymising work?
Anonymise keeps your JSON exactly as it is, the same records, keys, nesting and types, and replaces the values with made-up ones of the same kind, so you can share a bug report or a sample with a supplier without the people in it. True/false values, nulls and short lists such as "role": "admin" are kept, because they rarely identify anyone and make the data readable. The same value is always replaced by the same new value, so a customer who appears twice still appears twice. Free text such as comments becomes placeholder text, since that is where personal details hide. It is a help, not a guarantee: check the result before sharing it.
Are the email addresses and phone numbers real?
No, and they cannot reach anyone. Email and web addresses use example.com, example.org and example.net, which are reserved for examples. UK phone numbers come from the ranges Ofcom keeps for TV and radio drama, such as 07700 900123, and US numbers from 555-0100 to 555-0199. IP addresses come from the ranges reserved for documentation. Names and towns are real, common ones, combined at random; street names are made up.
Is my example sent anywhere?
No. The example and the generated data stay in your browser and are never stored, even with Remember settings ticked, which keeps only the mode, style, count and output format. Up to 10,000 records can be made at once; large jobs run in the background so the page stays responsive.