JSON Schema Generator

A JSON Schema describes the shape a JSON document is expected to have — which keys exist, what type each value should be, and which keys are required — so that tools, editors, and validators can check a payload without a human reading it line by line. It's the same idea as a database schema or a TypeScript interface, expressed in JSON itself.

Writing one by hand is tedious, so this tool infers it from a real example instead: paste a representative payload and it walks the structure, recording each field's type. When the sample is an array of objects, it looks across every item — a field present in every item becomes required, a field that only shows up sometimes becomes optional, and a field that's sometimes a string and sometimes null becomes a nullable string. Everything runs locally in your browser.

• •A schema inferred from one example is only as good as that example — if your real data has fields the sample doesn't, feed in a payload that covers those cases (or several merged together) before relying on the result.
• •Turn on "Strict" only once you're confident the sample's fields are the complete set — additionalProperties: false will reject any payload with an extra key, including harmless ones added later by an upstream API.
• •Turn off "Required Fields" when you want a permissive schema for validating loosely-structured or evolving data, and keep it on when you want to catch missing fields early.
• •Treat the generated schema as a starting point, not a final spec — review field names that look like they should have stricter constraints (enums, formats like "email" or "date-time", min/max) and add them by hand.