Data Formatters & Converters
Processed locally
Synthetic Data Generator from JSON Schema
Turn a JSON Schema into realistic, schema-valid fake data — deterministic from a seed, everything in your browser.
Generates as you type. Ctrl+Enter to re-run.
Supports type, properties, required, enum, const, items (min/maxItems), minimum/maximum, string formats (email, uuid, date-time, date, uri, hostname, ipv4), oneOf/anyOf/allOf, and internal $ref. Regex pattern is not generated.
How to use the Synthetic Data Generator
Paste a JSON Schema and get realistic, schema-valid sample records for tests, fixtures, demos, and seed data. The generator understands formats (email, uuid, date-time), enums, numeric ranges, arrays, and nested objects, and uses a seed so the output is reproducible. Everything runs in your browser; nothing is uploaded.
What it does
- Generates objects, arrays, strings, numbers, integers, booleans, and nulls per the schema.
- Produces format-aware strings: emails, UUIDs, dates, URLs, hostnames, and IPs.
- Respects enum, const, required, minItems/maxItems, and minimum/maximum.
- Resolves internal
$refand handles oneOf/anyOf/allOf.
When to use it
- Seeding a dev or QA database with realistic rows.
- Creating fixtures for unit, integration, or snapshot tests.
- Populating a demo or prototype with believable data.
- Generating request/response examples for an API contract.
How to use it
- Paste your JSON Schema.
- Set the record count, optional-field density, and seed.
- Copy or download the JSON array or NDJSON output.
Tips & pitfalls
- Keep the same seed for stable fixtures; change it for a fresh dataset.
- Regex
patternconstraints are not generated — add aformatorenumwhere you need specific shapes. - Validate the output with the JSON Schema Validator to confirm it matches your schema.
FAQ
- What JSON Schema features are supported? The generator honors type, properties, required, enum, const, items with minItems and maxItems, minimum and maximum for numbers, string formats like email, uuid, date-time, date, uri, hostname, and ipv4, plus oneOf, anyOf, allOf, and internal $ref references.
- Is the output reproducible? Yes. Generation uses a seeded random number generator, so the same schema and seed always produce the same data. Change the seed for a fresh dataset, or use the same seed to get stable fixtures.
- Is my schema uploaded anywhere? No. The schema is parsed and the data is generated entirely in your browser. Nothing is sent to any server.