JSON Schema Tools

11 tools · free · nothing uploaded

Draft 2020-12 is the default everywhere here, with 04 / 06 / 07 and 2019-09 available where the difference is real. If you are starting from data rather than from a spec, generate a schema first and feed it more than one sample — that is what makes the difference between every field being required and the optionality being right.

Start here

Schema generator Infer draft 2020-12 from one sample or several — more samples, better optionality. Schema validator Ajv across drafts 04 through 2020-12, with the failing instance path on every error. Schema → types TypeScript, Zod, Pydantic, Go or Rust generated from the schema rather than the data. Schema faker Plausible test fixtures that satisfy the schema, formats and constraints included. Schema diff Compare two versions and label each change breaking or backwards-compatible. OpenAPI extract Pull every component schema out of an OpenAPI spec as a standalone document.

Everything else in JSON Schema

Schema visualizer — Diagram a schema with $ref resolution.
Schema → Markdown — Readable field tables for a README or docs site.
Migrate draft — Draft-04 / 06 / 07 up to 2020-12.
Bundle $refs — Inline external refs into one self-contained schema.
Schema → OpenAPI — Emit an OpenAPI 3.0 or 3.1 component schema.

Why these run in your browser

There is no server-side processing here and no upload step: the page loads, and from then on the parsing, converting and rendering happen in this tab using your machine's CPU. That has three consequences worth knowing about. Your data stays on your machine, which matters when the JSON is a production payload with real customer records in it. There is no file-size limit imposed by us, only by how much memory your browser will give the tab. And once the page has loaded, it keeps working with the network off.

The trade is that very large documents are bounded by browser memory rather than by a beefy server — somewhere past 50 MB a textarea gets sluggish, and dropping the file in is better than pasting it. The privacy page spells out what is and is not collected.