Free mock JSON data generator
Build JSON fixtures with fields you define: fixed literals, random picks from your list, numeric ranges, booleans, UUIDs, and dates. Load a user/product/order template as a starting point, edit every field, then generate an array or single object — all in your browser.
How to use this tool
- 1
Open Mock JSON generator
Define fields and value rules for your API mock.
- 2
Edit fields or load a template
Set names, modes, fixed values or pick lists, then choose count and seed.
- 3
Copy or download
Copy the JSON or download mock-data.json.
Quick facts
| Runs locally? | Yes — generation uses your field rules in this tab only. |
|---|---|
| Is anything uploaded? | No. Fixtures stay on your device. |
| Repeatable data? | Use a numeric seed with the same fields to reproduce output. |
| Pair with other JSON tools? | Format with the JSON formatter or infer types with JSON to TypeScript. |
Top use cases
- Custom field names and value rules, optional templates, seed, up to 50 rows — local only.
- Runs locally?: Yes — generation uses your field rules in this tab only.
- Is anything uploaded?: No. Fixtures stay on your device.
- Repeatable data?: Use a numeric seed with the same fields to reproduce output.
- Pair with other JSON tools?: Format with the JSON formatter or infer types with JSON to TypeScript.
FAQ
Can I set exact values?▾
Yes — choose Fixed value and enter text, numbers, booleans, or JSON literals.
Random from my own list?▾
Use Random pick and enter one option per line.
What do templates do?▾
They only load editable example fields; you can change names, modes, and values freely.
Maximum rows?▾
Fifty per generation to keep the tab responsive.
Seeded vs random?▾
Leave seed empty for different data each time; set a seed for stable test fixtures.
Valid JSON?▾
Yes — output is pretty-printed JSON you can parse immediately.