JSON to JSON Schema Generator

Paste a JSON sample and generate a draft 2020-12 JSON Schema — types, properties and required fields inferred, live in your browser.

This json to json schema generator does the opposite of a schema viewer: instead of rendering a schema you already have, it reads a sample document and writes one. It infers types (down to integer vs number), builds the properties map, and lists required fields — for an array of objects it merges every element and marks a key required only when it appears in all of them. That makes it quick to infer schema from json for validation, documentation, or an OpenAPI model. Need to read a schema back afterwards? Pair it with our JSON Schema viewer, which draws a schema as a tree and validates data against it.

Draft 2020-12 · inferred from your sample
JSON sample
JSON Schema

How it works

  1. 1

    Paste JSON

    Drop a representative document in the left pane. An array of similar objects gives the most accurate required list.

  2. 2

    Read the schema

    The right pane fills with a live draft 2020-12 schema — type, properties, items and required, all inferred from your sample.

  3. 3

    Copy or download

    Copy the schema or save it as a schema.json file to drop into your validator or docs.

Instant & 100% private — nothing is uploaded

Everything runs locally in your browser. Your code, text and files are processed on your own device and are never sent to a server — so there are no upload waits, no size limits from us, and nothing is ever stored or logged.

Frequently asked questions

Which JSON Schema draft does it output?
Draft 2020-12. The root carries the matching $schema URI so validators know exactly which dialect to apply.
How does it decide the required fields?
For a single object every key is required. For an array of objects, this json schema generator marks a key required only if it appears in every element.
Does it tell integers apart from other numbers?
Yes. A whole number is typed "integer" and a fractional one is typed "number", so the inferred schema is tighter than a plain number-for-everything guess.
How is this different from the JSON Schema viewer?
This tool generates a schema from sample data. The viewer goes the other way — it visualises an existing schema as a tree and validates documents against it. They pair well.
Is anything uploaded?
No. The schema is inferred locally in your browser, so your sample data never leaves the page.

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