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JSON Schema Generator

Infer a JSON Schema draft 2020-12 document from any JSON sample, with types, required keys and string formats.

Infer a JSON Schema

Inferred: —
The output targets JSON Schema draft 2020-12 and is inferred locally from the sample you paste.

How to use the JSON Schema Generator

  1. Paste a JSON sample that represents the data you receive.
  2. Press Generate schema to infer types, required keys and formats.
  3. Copy the draft 2020-12 schema and drop it into your project.

Features

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Frequently Asked Questions

Common questions about the free online json schema generator.

Paste a representative JSON sample and press Generate schema. The tool infers types, required keys and formats instantly.
The generated document targets JSON Schema draft 2020-12 and declares that draft in its schema property.
Every key found in the sample is listed as required, because the sample is treated as one complete record.
Dates, date-time stamps, email addresses, URIs and UUIDs are recognised from the shape of the values and tagged with a format.
Array items are compared and merged, so a mixed array produces one items schema that covers every element type.
A null value widens the inferred type to include null, so optional or empty fields are described accurately.
No. Parsing and inference happen entirely in your browser, so the data you paste never leaves your device.
Yes. The output is plain JSON, so you can copy it and adjust descriptions, limits or examples by hand.
Yes. The generator is completely free, needs no account and has no usage limits.

Last updated: October 10, 2026