Mock / Fake JSON Data Generator
Don't have a schema handy? Infer one from real samples with the JSON Schema tool. Cmd/Ctrl+Enter saves the current schema to history.
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Paste a JSON Schema, get fake data matching that shape — useful for seeding test fixtures or previewing what an API response will look like before the real data exists. Pair it with the JSON Schema tool: infer a schema from real samples there, then mock more data in that exact shape here.
Frequently asked questions
- What input does it expect — sample JSON or a schema?
- A JSON Schema, not a sample. If you have sample data instead, generate a schema from it first with the JSON Schema tool — the two are designed as a pair: infer a schema from real samples, then mock more data in that exact shape.
- Does the same seed always produce the same output?
- Yes — generation uses a seeded pseudo-random generator, so the same schema and seed reproduce identical output every time. That makes it usable for repeatable test fixtures, not just one-off examples.
- Is the random data cryptographically secure?
- No, and it doesn't need to be — this is fake test data, not security-sensitive output, so a fast, seedable, non-cryptographic generator is the right tool here.
- Is my schema uploaded anywhere?
- No. Generation happens locally in your browser tab — nothing is sent to a server.
Read the full guide for this tool →
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