How to use the JSON to JSON Schema
- Paste a JSON example — an API response, a config file, a database record — or click Sample.
- For better results paste several examples as a JSON array: fields missing from some become optional, and different types become a union.
- Choose the draft, how required is decided, and whether to detect formats, build enums, forbid extra properties or keep examples.
- Copy or download the schema — or send it straight to the JSON Schema to TypeScript converter or the validator.
How the schema is inferred
- Types: strings, numbers, integers (whole numbers), booleans, null, objects and arrays. A field that is sometimes a number and sometimes null becomes
"type": ["number", "null"]. - Arrays: every item is merged into one
itemsschema, so an array of user objects gets one user schema with all keys seen. - Required: by default a key is required only if it appears in every object of that shape. With one example, all keys are required.
- Formats: strings that all look like an email, URI, UUID, date, date-time, time, IPv4 or IPv6 get a
format. - Enums: a string field with a few repeating values across many examples (like
status) becomes anenum.
An inferred schema describes your examples, not your intent — review it: tighten strings with minLength or pattern, add minimum/maximum to numbers and decide which fields are truly optional. Then check data against it with the JSON Schema Validator or generate types with JSON Schema to TypeScript.
Also searched as: json schema generator, generate json schema from json, infer json schema, json schema from example, create json schema online, json schema draft 2020-12, json to schema.
Tools that pair well with the JSON to JSON Schema
- Mock Data Generator — Create up to 10,000 rows of realistic test data — users, products, orders, addresses, companies or nested API records — or build your own schema.
- JSONPath Tester — Type a JSONPath query and instantly see what it selects — with the exact path of each match.
- JSON to YAML — Paste JSON and get clean YAML for Kubernetes manifests, Docker Compose, GitHub Actions or any config file.
- YAML to JSON — Paste YAML — a Compose file, Kubernetes manifest or CI config — and get formatted JSON.
Frequently asked questions
How do I generate a JSON Schema from JSON?
Paste the JSON here: the generator walks every value, writes the matching type, properties and items, marks keys as required and detects formats. Paste several examples in an array for a more accurate result.
Which JSON Schema draft should I use?
Draft 2020-12 is the current version and what OpenAPI 3.1 uses. Choose draft-07 for older tools and libraries that don’t support 2020-12 yet.
Why is a field not marked as required?
It was missing from at least one of your examples. Change “Required fields” to “Every key” if every field must always be present.
Can I turn the schema into TypeScript types?
Yes — click To TypeScript to open the schema in the JSON Schema to TypeScript converter.
Can I install JSON to JSON Schema as a web app and use it offline?
Yes. JSON to JSON Schema is an installable web app (PWA) — installed from your browser, not downloaded from an app store. Click Install app at the top of this page in Chrome or Edge (Windows, macOS, Linux, ChromeOS) or on Android, use Share → Add to Home Screen on iPhone and iPad, or File → Add to Dock in Safari 17+ on a Mac. It then opens in its own window with its own icon, and because it runs entirely in your browser it keeps working offline. Firefox on desktop can’t install web apps. How installing works.