JSON Schema Generator inspects a pasted JSON object or array and creates a practical starter schema. It is useful for API documentation, validation setup, mocks, and contract reviews.
Infer a starter JSON Schema from a sample JSON object or array. Everything runs locally in this tab.
{
"type": "object",
"required": [
"id",
"email",
"active"
],
"properties": {
"id": {
"type": "number"
},
"email": {
"type": "string"
},
"active": {
"type": "boolean"
}
}
}Yes. The tool is free and runs directly in your browser with no account required.
No. The schema is inferred locally in the browser tab and your JSON is not sent to a server.
Quickly generating a starter JSON Schema from a real example object — useful as a first draft for API documentation or a validation library.
It inspects the sample value's JavaScript type at each key: objects become 'object' with nested properties, arrays become 'array' with an 'items' schema inferred from the first element, and primitives map to 'string', 'number', 'boolean', or 'null'.
Yes — every property present in your sample JSON is listed in the schema's 'required' array, since the generator has no way to know which fields are optional from a single example.
It looks only at the first element of the array and infers the schema from that. If your array contains mixed types across elements, only the first element's shape is reflected.
No — it infers basic JSON Schema types only (string, number, boolean, object, array, null). Format keywords, patterns, and value constraints (minLength, minimum, etc.) need to be added manually.
The tool reports a parsing error message instead of a schema, so you can fix the JSON syntax before retrying.