JSON schema generator

Infer a JSON Schema (draft 2020-12) from a sample JSON document, with optional format detection.

Inferred in this browser. Nothing is sent anywhere.

Types are inferred from the sample only — a string that happens to look like a date gets a format hint, not a guarantee. Arrays merge their item shapes; mixed items become anyOf. Integers vs numbers are distinguished. Up to 488 KB.

How to use

  1. Paste a JSON sample.
  2. Choose whether to detect string formats.
  3. Copy or download the schema.

What it supports

Infers object, array, string, boolean, number, integer, and null; merges item schemas across arrays. Optional detection of date-time, date, UUID, email, and URI formats — detection is a heuristic, not proof. Input up to 500 KB.

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