What does this tool do?

It generates deterministic fake records with generateSyntheticData from a schema (enums, email/name/date/uuid/ipv4 formats, ranges, nested objects, arrays) and serializes with formatSyntheticData to json, jsonl, or csv.

How do seeds and counts behave?

The same seed and count return deep-equal records (capped at 1000) while a new seed reshuffles; JSONL emits exactly one object per line so line count equals the requested count.

Is my schema uploaded or stored?

No. The Mulberry32 PRNG, value generation, and serialization run fully client-side.

Why do extra fields appear, or UUIDs look odd?

Every declared property is generated on each record regardless of required, and UUIDs follow v4 shape (4 in the version slot, 8/9/a/b variant) by construction.

Synthetic Data Faker

Generate deterministic synthetic datasets locally from a JSON Schema

Define your schema

Quick templateJSON Schema

RecordsSeed

Output format

Everything runs in your browser. No schema or generated data is uploaded.

10 records · seed 42

[
  {
    "id": "4ec76e63-5e1b-4f4e-bb38-ce650480b7b8",
    "name": "Ada Chen",
    "email": "7si97nh@example.com",
    "joined": "2025-10-13",
    "role": "viewer"
  },
  {
    "id": "c2c5c123-7b53-4cbe-bb57-ca2a84501a36",
    "name": "Ada Garcia",
    "email": "ijzwi7t@example.com",
    "joined": "2017-12-06",
    "role": "editor"
  },
  {
    "id": "07f98e5f-584a-4507-bef3-5f59dc4a7df3",
    "name": "Iris Lee",
    "email": "ps6jhzz@example.com",
    "joined": "2002-02-22",
    "role": "admin"
  },
  {
    "id": "b324e6bb-0099-42cb-847c-58d715ce19a1",
    "name": "Iris Yilmaz",
    "email": "i87usob@example.com",
    "joined": "2007-10-10",
    "role": "editor"
  },
  {
    "id": "76a02aa3-7c44-4624-8c06-65c8d7357e0e",
    "name": "Zoe Demir",
    "email": "r9o2gdh@example.com",
    "joined": "2012-03-03",
    "role": "viewer"
  },
  {
    "id": "299e6ad3-7831-4e2f-a9cc-77365836b150",
    "name": "Ada Brown",
    "email": "6j767ta@example.com",
    "joined": "2010-11-11",
    "role": "editor"
  },
  {
    "id": "ca7cf09a-919b-4d18-899e-783c4c3d5f00",
    "name": "Maya Stone",
    "email": "9tsu144@example.com",
    "joined": "2017-10-13",
    "role": "admin"
  },
  {
    "id": "316e67bf-d8ab-4211-bac5-92165fe12a3d",
    "name": "Iris Demir",
    "email": "cqdeu0g@example.com",
    "joined": "2029-02-13",
    "role": "admin"
  },
  {
    "id": "4302705e-0b25-47cc-819d-8206a8e31251",
    "name": "Lina Garcia",
    "email": "im1ojx0@example.com",
    "joined": "2013-03-18",
    "role": "admin"
  },
  {
    "id": "692326f7-bb60-4cb0-9165-10aef217088c",
    "name": "Zoe Smith",
    "email": "r0nx1wz@example.com",
    "joined": "2020-07-07",
    "role": "viewer"
  }
]

Generated preview

10 records · seed 42

[
  {
    "id": "4ec76e63-5e1b-4f4e-bb38-ce650480b7b8",
    "name": "Ada Chen",
    "email": "7si97nh@example.com",
    "joined": "2025-10-13",
    "role": "viewer"
  },
  {
    "id": "c2c5c123-7b53-4cbe-bb57-ca2a84501a36",
    "name": "Ada Garcia",
    "email": "ijzwi7t@example.com",
    "joined": "2017-12-06",
    "role": "editor"
  },
  {
    "id": "07f98e5f-584a-4507-bef3-5f59dc4a7df3",
    "name": "Iris Lee",
    "email": "ps6jhzz@example.com",
    "joined": "2002-02-22",
    "role": "admin"
  },
  {
    "id": "b324e6bb-0099-42cb-847c-58d715ce19a1",
    "name": "Iris Yilmaz",
    "email": "i87usob@example.com",
    "joined": "2007-10-10",
    "role": "editor"
  },
  {
    "id": "76a02aa3-7c44-4624-8c06-65c8d7357e0e",
    "name": "Zoe Demir",
    "email": "r9o2gdh@example.com",
    "joined": "2012-03-03",
    "role": "viewer"
  },
  {
    "id": "299e6ad3-7831-4e2f-a9cc-77365836b150",
    "name": "Ada Brown",
    "email": "6j767ta@example.com",
    "joined": "2010-11-11",
    "role": "editor"
  },
  {
    "id": "ca7cf09a-919b-4d18-899e-783c4c3d5f00",
    "name": "Maya Stone",
    "email": "9tsu144@example.com",
    "joined": "2017-10-13",
    "role": "admin"
  },
  {
    "id": "316e67bf-d8ab-4211-bac5-92165fe12a3d",
    "name": "Iris Demir",
    "email": "cqdeu0g@example.com",
    "joined": "2029-02-13",
    "role": "admin"
  },
  {
    "id": "4302705e-0b25-47cc-819d-8206a8e31251",
    "name": "Lina Garcia",
    "email": "im1ojx0@example.com",
    "joined": "2013-03-18",
    "role": "admin"
  },
  {
    "id": "692326f7-bb60-4cb0-9165-10aef217088c",
    "name": "Zoe Smith",
    "email": "r0nx1wz@example.com",
    "joined": "2020-07-07",
    "role": "viewer"
  }
]

About

Build privacy-friendly test datasets in your browser. Define properties, required fields, enums, ranges, string lengths, and email, name, date, UUID, or IPv4 formats; the same seed always produces the same records.

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