JSON to JSON Schema Converter

About the JSON to JSON Schema converter

JSON Schema is the portable way to describe the shape of a document — understood by validators in every language, and by OpenAPI, which embeds it directly.

Writing one from scratch for a large payload is slow. Paste an example and get a complete draft 2020-12 schema to edit down.

What is inferred

Object properties with their types, `required` listing every field that was present and non-null, `additionalProperties: false`, and `items` for arrays taken from the first element.

Numbers are split into `integer` and `number` depending on whether the sample had a fractional part.

What to check before using it

`required` is the assumption most likely to be wrong: a field appearing in one sample is not necessarily mandatory. Trim that list to the fields the API genuinely guarantees.

`additionalProperties: false` is strict by design, so a schema that passes today fails the moment the API adds a field. That is often what you want in a test and rarely what you want in production — relax it if you need forward compatibility.

Types come from one sample

Everything here is inferred from the JSON you paste. A field that happens to be absent from your example will be absent from the output, and a field that is null in the sample cannot be typed at all — only marked as nullable.

Paste the richest response you have, then review the optional and nullable fields by hand. Treat the result as a fast first draft rather than a schema.

Frequently asked questions