JSON Schema Generator & Validator

Infer a JSON Schema from a sample document, or validate JSON against a schema you already have.

Sample JSON

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About this tool

A JSON Schema turns "what this data should look like" from a comment into something a computer can check — the same document that catches an accidentally-string number in one API endpoint's payload. Writing one by hand for a real payload is tedious; validating a payload against one you already have shouldn't need a build step.

How to use it

Generate mode: paste a representative sample JSON value, get back an inferred Draft-07-style schema.
Validate mode: paste a schema and a JSON document, and see every rule it violates, with its exact path.

Examples

Inferring from a sample

{ "name": "Ada", "age": 30, "tags": ["engineer"] }

A schema requiring an object with a string name, integer age and array-of-strings tags.

Common problems

Validation reports errors on a schema I copied from another tool.: This engine covers the common Draft-07/2020-12 keywords (type, properties, required, enum, pattern, numeric ranges, oneOf/anyOf/allOf, same-document $ref) but not the full vocabulary system or external $refs — a schema leaning on those will need trimming to what this checks.