DevToolsmith

Mock Data Generator

Build repeatable test fixtures from a list of named fields. Choose English or Simplified Chinese values, a row count and a seed, then export JSON, CSV, TSV, XML or SQL without a server.

Runs 100% in your browser — nothing is uploaded

Generated test data
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Synthetic data for testing. The same fields, language, seed and library version reproduce the same output. Dates use a fixed 2020–2030 range. Email addresses use example domains. IP and MAC values are synthetic test fixtures; CSV and TSV protect spreadsheet formula prefixes. XML exports scalar field values as text.

Choose columns for your fixture

Start with id, name, email and created_at, then add fields such as city, country, company, boolean, integer or UUID. Names must be unique ASCII identifiers. Up to twelve fields and ten thousand rows are supported.

Reuse the result

For a minimal fixture, set two fields: id with type ID and active with type Boolean. Choose English, three rows, seed 42 and JSON output. The current generator produces:

[
  {
    "id": 1,
    "active": true
  },
  {
    "id": 2,
    "active": false
  },
  {
    "id": 3,
    "active": false
  }
]

Keep the seed, field order and library version stable when snapshot tests depend on these values. Adding a new field may consume random draws and change later generated values. A seed makes a test repeatable; it does not turn fake data into a representative production dataset.

JSON output can be sent to the existing conversion and SQLite tools. CSV and TSV output quote separators and prefixes text that could be interpreted as a spreadsheet formula. XML output wraps scalar field values in named elements. SQL output contains INSERT statements for a table named mock_data; create a compatible table before running them.

Keep test data repeatable

Set a fixed seed to compare output across test runs. The generator loads only the selected English or Chinese locale and runs in a cancellable worker. Generation has a twenty-second timeout and a two-million-character output limit.

Send fixture JSON to JSON to TypeScript, inspect it with JSON Viewer, or compare it with an existing JSON Schema. Use JSON Schema to Example when the schema, rather than a field list, must drive the generated record.

Powered by open-source software. Third-party licenses.

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Frequently asked questions

Will the same seed reproduce the output?

The same fields, order, language, seed and Faker version produce the same values. Date generation uses a fixed 2020–2030 reference range. Updating the library can change generated values.

Does this create real personal information?

Values are synthetic test fixtures and may coincidentally resemble real people or places. Email fields use example domains. Generated values are not passwords or authentication secrets.

How is this different from Schema to Example?

This tool builds a table from user-selected field types. JSON Schema to Example generates a record that is checked against a supplied schema. This generator does not validate against a schema.

Sources

Spotted a mistake? Email hello@devtoolsmith.com and we’ll fix it.