JSON Schema Generator

What JSON schema generation does

A JSON schema generator infers a Draft 07-style schema from one JSON sample. Objects become type: object with properties and required keys from that sample. Arrays get an items schema merged from the items that were present. The tool runs in the browser. Nothing is uploaded.

This is a starting point, not a complete API contract. A sample cannot tell you which keys are optional, which strings are enums, or which numbers have a maximum. If you treat the generated schema as the whole truth, later payloads will fail for honest reasons — extra keys you did not see, or missing keys you assumed were required.

How to use

1. Paste JSON. Empty input is not a value.
2. Choose Generate schema. Example loads a small nested object.
3. Copy output writes the schema. Clear empties both boxes.

Invalid JSON is not converted. Edit required and add additionalProperties before you use the result as a gate. You can paste the output into the JSON Schema Validator, which evaluates the same keyword subset this generator emits.

Example

{
  "id": 1,
  "name": "Ada",
  "tags": ["admin"]
}

The schema should list id as a number, name as a string, and tags as an array of strings, with those three keys required. That matches this sample. It does not prove email will never appear.

When to use it

Use generation when you have a fixture and want a first schema file. If you only need names, use the JSON Key Extractor. If you need to see nesting, use the JSON Viewer first.

The emitted document sets $schema to the Draft 07 URI so editors recognize it. It does not invent title, description, or examples. Integer-looking numbers still become type: number, because JSON does not distinguish integer from float at parse time in a way this tool relies on.

When an array contains both objects and strings, the item schema becomes a type list. That is weaker than a real oneOf, and the companion validator does not evaluate oneOf. Prefer homogeneous arrays in the sample if you want a simple items schema. Two objects in an array share one merged property set; a key that appears in only one object is not marked required on the item schema.

After you generate, decide whether unknown keys should be allowed. This generator does not set additionalProperties. Add false if the contract is closed. Then validate a second, different payload — a schema that only ever sees one fixture is not yet a contract. Keep the sample small enough to understand. A megabyte dump will hit the node limit and produce nothing. Review required keys before you enforce the file in continuous integration.

Limits

• No $ref, enum, format, or combinators are inferred.
• Required keys are exactly the keys in this sample.
• Mixed array items merge types. Empty arrays have no items.
• Traversal stops after 4000 nodes. Output is then cleared.

The procedure is how to generate and check a JSON Schema. For the definition, read what JSON Schema is.

Privacy

Parse and inference run in this browser. The payload is not sent to YallaSolve for this tool.