Why this random JSON generator?
- Generate JSON test data without uploads (browser-only).
- Build a schema from templates or custom fields.
- Export as JSON array or NDJSON for pipelines.
- Share settings safely: URLs never include schema or generated data.
How to use (3 steps)
- Pick a template or define fields.
- Set records, output format, and RNG mode.
- Generate, preview, then copy or download.
Generate
Random JSON generator
Define fields (name/type/params), generate records, then copy or download JSON output.
How to use Random JSON Generator well
Start with a schema that matches the shape you actually need, then generate a small sample before you scale up. This keeps field names, uniqueness rules, and date ranges understandable before you export large fixture sets.
Build the schema first
Pick the closest template, then adjust names, field types, null rate, and uniqueness one column at a time. Use import/export if your team needs to review or reuse the same schema later.
Choose the output for the next tool
Use JSON array when people will inspect or pretty-print the result. Use NDJSON when another script, loader, or log-style pipeline expects one object per line.
Use seeded mode only for repeatability
Seeded mode helps you recreate the same fixture set across sessions or teammates. Secure mode is better when you want less predictable samples and you do not need exact replay.
Check uniqueness before large runs
- If a field has a tiny value space, unique generation can fail even when the schema looks valid.
- Generate a small sample first to verify email domains, token length, and choice weights.
- Share URLs are safe for settings review, but they never include your schema or generated output.
See also
FAQ
Is my data uploaded?
No. Everything runs locally in your browser.
Can I share generated JSON with a URL?
Share URLs include settings only. Use copy/download to share data.
Is seeded mode secure?
No. Seeded mode is for reproducibility only.
Why can unique generation fail?
If the value space is too small, duplicates may be unavoidable.
When should I use seeded mode instead of secure mode?
Use seeded mode when you need reproducible test fixtures. Use secure mode when you want less predictable values or you plan to share sample output externally.
How to plan reproducible JSON fixtures
Choose schema before scale
The most expensive mistake is generating thousands of rows with the wrong field names or type assumptions. Validate a small sample, confirm field order, then increase record count.
Pick the export format for the next consumer
Array output is easier for people, screenshots, and manual inspection. NDJSON is usually the better handoff for streaming tools, loaders, and log-like workflows.
Use seeded mode for fixture parity
If QA, docs, and backend tests need the same sample again, keep a short seed and store the schema JSON alongside the expected output. If you only need fresh sample data, stay in secure mode.
Review uniqueness and null rate together
Unique fields, narrow ranges, and non-zero null rate interact quickly. Revisit those assumptions when output size grows or when another tool starts rejecting the generated data.