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Plate IV · Developer, API & Database Seeding Utilities

JSON Mock Data Generator

Arrays, envelopes, keyed objects or NDJSON from thirty-three field types.

json
[
  {
    "id": 1,
    "fullName": "Alice Young",
    "email": "alice.young@example.com",
    "city": "Boise",
    "isActive": true,
    "createdAt": "2025-11-01T21:05:30Z"
  },
  {
    "id": 2,
    "fullName": "Ryan Lopez",
    "email": "ryan.lopez@example.com",
    "city": "Brooklyn",
    "isActive": true,
    "createdAt": "2026-01-09T21:05:30Z"
  },
  {
    "id": 3,
    "fullName": "Linda Anderson",
    "email": "linda.anderson@example.com",
    "city": "Savannah",
    "isActive": false,
    "createdAt": "2026-01-21T21:05:30Z"
  },
  {
    "id": 4,
    "fullName": "Iris Martin",
    "email": "iris.martin@example.com",
    "city": "Portland",
    "isActive": true,
    "createdAt": "2024-02-09T21:05:30Z"
  },
  {
    "id": 5,
    "fullName": "Thomas Moore",
    "email": "thomas.moore@example.com",
    "city": "Boise",
    "isActive": true,
    "createdAt": "2025-05-06T21:05:30Z"
  }
]
42 lines · 898 BGenerated in your browser · JSON Mock Data Generator

Pick your fields once and take them out in whichever shape your consumer expects. The same field list drives the SQL, CSV, XML and GraphQL tools too, so a fixture stays consistent as it moves between them.

What you can control

  • Four root shapes, including NDJSON for anything that streams records line by line.
  • Address fields can nest under an address object, matching how most APIs actually structure them.
  • Null injection sprinkles nulls through optional fields at about one in twelve — enough to find the code that assumes a value is always present.
  • Thirty-three field types, each with a sensible generator behind it rather than a random string.

What this is not

Field names are fixed by the tool. If your schema uses different names, generate here and rename in your editor, or use the schema builder, which takes arbitrary paths.

Questions

Can I control the field names?

Not in this tool — they are fixed to the type names. The schema builder takes arbitrary dotted paths and lets you map any name onto any type.

What is NDJSON for?

Streaming. One JSON object per line means a consumer can process records as they arrive instead of waiting for the closing bracket. Log pipelines and bulk-import APIs both use it.

Why inject nulls?

Because most crashes in data-handling code come from a field that was always present in development and absent once in production. Injecting nulls finds those paths early.

Next in Developer

All 11 →

SQL INSERT Statement Generator

Seed scripts for PostgreSQL, MySQL, SQLite and SQL Server.

CSV & TSV Dataset Generator

Delimiters, quoting, line endings and BOM — all the things that break imports.

GraphQL Mock Generator

SDL schemas, query documents, mutations and response payloads.