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JSON Schema Faker
What it is
JSON Schema Faker generates synthetic JSON data from JSON Schema definitions. It supports JSON Schema 2019-09 and 2020-12, and a numeric seed can make generated output deterministic. The `jsf` command can read schema files, write JSON to a file, and generate multiple items as an array. Reference handling includes `$ref` resolution with cycle detection, configurable recursion depth, and remote reference resolution. Generators cover formats such as email, date-time, URI, IP addresses, and UUID; regex patterns are supported through an AST-based string generator. Users can register custom formats and keyword generators, while optional extensions support faker.js and chance.js. YAML output requires the YAML package through an extension. The project works in Node.js and browsers and is built for Bun and Node.js; deployment is self-hosted. It is open source under the MIT License, with a listed price of free and zero production dependencies. Synchronous generation only supports schemas that resolve without I/O; asynchronous resolvers or extensions cause it to throw.
For and against
For
- Supports JSON Schema 2019-09 and 2020-12
- Numeric seeds enable deterministic results
- Custom formats and keyword generators are supported
- Zero production dependencies
- MIT licensed and free
Against
- Synchronous generation cannot handle schemas requiring I/O
- Asynchronous resolvers or extensions cause it to throw
- YAML output requires an extension and YAML package
The verdict
JSON Schema Faker offers schema-based synthetic data generation with reference handling and customization options. Note the synchronous I/O restriction and the extra requirements for YAML output.
Who it suits
It suits developers who need synthetic JSON output from schema definitions in Node.js or browser environments. Self-hosted deployment and CLI use may fit local development workflows.
Plans and prices
JSON Schema Faker
MIT License · npm and Bun installation
Read 7 Oct 2026 · json-schema-faker.js.org
On the record
- CLI
- The `jsf` command can generate JSON from schema files, write to a file, and generate multiple items as an array.json-schema-faker.js.org · read 7 Oct 2026
- Customization
- Users can register custom formats and define custom keyword generators.json-schema-faker.js.org · read 7 Oct 2026
- Dependencies
- The project describes itself as having zero production dependencies.json-schema-faker.js.org · read 7 Oct 2026
- Formats and patterns
- It includes generators for common formats such as email, date-time, URI, IP addresses, and UUID, and supports regex patterns with an AST-based string generator.json-schema-faker.js.org · read 7 Oct 2026
- Integrations
- Optional extensions support faker.js and chance.js, and YAML output requires the YAML package through an extension.json-schema-faker.js.org · read 7 Oct 2026
- License
- The site identifies the project as MIT licensed.json-schema-faker.js.org · read 7 Oct 2026
- Limit
- Synchronous generation only supports schemas that resolve without I/O; asynchronous resolvers or extensions cause it to throw.json-schema-faker.js.org · read 7 Oct 2026
- Maker details
- The official site and repository page opened do not identify a company headquarters or founding year.github.com · read 7 Oct 2026
- Purpose
- JSON Schema Faker generates valid JSON data from JSON Schema definitions.json-schema-faker.js.org · read 7 Oct 2026
- References
- It supports `$ref` resolution with cycle detection, configurable recursion depth, and remote reference resolution.json-schema-faker.js.org · read 7 Oct 2026
- Reproducible output
- A numeric seed produces deterministic output, with the same seed producing the same results.json-schema-faker.js.org · read 7 Oct 2026
- Runtime
- The project says it works in Node.js and browsers and is built for Bun and Node.js.json-schema-faker.js.org · read 7 Oct 2026
- Schema support
- The project states that it supports JSON Schema 2019-09 and 2020-12.json-schema-faker.js.org · read 7 Oct 2026
- Security and compliance
- The official site and repository pages opened do not state security certifications or compliance claims.github.com · read 7 Oct 2026
