JSON Schema Generator

Infer a JSON Schema (draft 2020-12) from a JSON sample

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Ideal for LLM structured output (OpenAI/Anthropic tool calling), API validation with ajv, or documenting a payload. All fields in the sample are marked required - remove any that are optional.

So funktioniert's

  1. 1
    Paste a JSON sample

    Drop a representative object or array - an API response, a config, an LLM function call payload.

  2. 2
    Name the root type

    Give the schema a title (defaults to 'RootSchema'). Used by generators and error messages.

  3. 3
    Copy the schema

    Paste directly into your LLM tool definition, ajv, or API docs.

Über JSON Schema Generator

Free online JSON Schema generator. Paste a JSON sample to instantly get a draft-2020-12 JSON Schema with types, required fields, and nested object/array shapes. Ideal for LLM structured output (OpenAI/Anthropic tool calling), ajv validation, and API contracts. JSON Schema Generator auf 712 Tools läuft komplett in deinem Browser über native JavaScript APIs - kein Server sieht je deine Daten. Das heißt: sofortige Ergebnisse, volle Privatsphäre und keine Upload-Limits.

Ob für eine Debugging-Session, einen schnellen Sanity Check oder einen Produktions-Incident - dieses Tool ist kostenlos so oft nutzbar, wie du willst. Keine Wasserzeichen, kein Signup und keine Ads im Tool selbst.

Häufige Fragen

Which JSON Schema draft?

Draft 2020-12 - the current version, and what OpenAI and Anthropic expect for structured output / tool calling.

Are all fields marked required?

Yes - every field in your sample. Remove the ones that are conditional from the required array by hand.

How are arrays typed?

The tool merges all items and produces one items schema. Mixed arrays become a union of types.

Is my JSON sent anywhere?

No. Inference happens entirely in your browser.

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