vtree — free JSON Schema generator. Paste JSON and get a JSON Schema back instantly, with types, string formats, and required fields inferred automatically, entirely in your browser.

Features

• Generate a JSON Schema from any JSON document
• Detects string formats — email, UUID, URL, and date-time
• Infers integer vs. number, and marks every observed field required
• Runs entirely in the browser — no data leaves your device

Frequently asked questions

What does the generated schema mark as required?

Every field present in your example document — the schema is inferred from the one document you paste, so there's no way to know which fields are truly optional without seeing more examples. Remove a required entry by hand for any field that isn't always present.

Does it detect string formats like email or UUID?

Yes — values that look like an email address, a UUID, a URL, or an ISO 8601 date become format: "email", "uuid", "uri", or "date-time" in the output, instead of a plain string.

How are arrays handled?

The schema for an array's items is inferred from its first element — a mixed-type array won't get a schema that covers every variant, just the first one.

Is my data uploaded anywhere?

No. The schema is generated entirely in your browser.

Is this free to use?

Yes, vtree is free with no account or sign-up required.