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.

使い方

  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.

JSON Schema Generator について

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. 712 Tools の JSON Schema Generator はモダンな JavaScript API を使って完全にブラウザ内で動作します - サーバーがあなたのデータを見ることは一切ありません。つまり、即時の結果、完全なプライバシー、アップロード制限なしです。

デバッグ、簡単な確認、あるいは本番のインシデント対応まで - このツールは何度でも無料で使えます。ウォーターマークなし、サインアップなし、ツール内広告なし。

よくある質問

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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JSON Schema for LLM structured output: the developer's shortcut

OpenAI's structured output and Anthropic's tool use both want JSON Schema. Here's the draft that works everywhere, the fields models care about, and how to write one from an example in 10 seconds.

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