JSON to JSON Schema Generator

One sample makes a first draft

Inference only knows the values it was shown. A field that holds 150 in the sample becomes integer, and the schema then rejects the next record where it is 149.99. A field that is null in the sample allows only null. Every string is just string, with no length, pattern, or format. Feed in a sample that holds the variety real data has, or loosen those types by hand. Arrays are the exception: every element is read, so a list of records whose fields vary produces one merged item schema, and only keys present in every element stay required.

Tightening the result

The generated schema says what types appear, not what values are allowed. Add enum for fields with a fixed set of values, format: "email" or format: "date-time" where it applies, minimum for amounts, and additionalProperties: false if unknown keys should be rejected; without it, extra keys pass. The JSON Schema validator checks the result, including format and additionalProperties, against real payloads. To produce types for code from the same sample, use JSON to TypeScript.

How to use it

1. Paste a sample JSON payload.
2. Configure schema options (required fields, descriptions).
3. Copy or download the generated JSON Schema definition.

Privacy & limitations

JSON parsing and schema generation run strictly inside local browser memory.