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JSON to JSON Schema

Generate JSON Schema documents from JSON samples. Types, required arrays, nested properties, and formats are inferred automatically.

JSON input

Paste JSON, optionally name the root type, then generate.

Your JSON Schema code will appear here.
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A contract from an example

JSON Schema is usually written before the data exists, but often you have the data first. This tool reverses the flow: feed it a representative payload and get a draft 2020-12 schema documenting every observed field.

Validate configs and APIs

Use the schema to validate config files at startup, API responses in tests, or user submitted JSON in admin tools. Ajv and Python's jsonschema both consume the output directly.

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JSON to JSON Schema FAQs

What is JSON Schema for?
JSON Schema is a standard vocabulary for describing JSON documents. Validators use it to check API payloads, config files, and form data against the declared shape.
How is the required array built?
Keys present in every sampled object land in required. Keys missing from some records stay optional, so the schema reflects observed reality.
Which draft does the output use?
The generator emits draft 2020-12, the current JSON Schema version, with $schema declared so validators pick the right dialect.
Does it detect formats like email or date?
String values are checked against common patterns: emails get format email, ISO dates get format date-time, which enables stricter validation for free.
Can I validate with this in JavaScript?
Yes. Libraries like Ajv compile the generated schema into a fast validator function you can run on any payload.
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