Free JSON Schema Generator

Paste a JSON sample and get a JSON Schema that describes it. The output uses the strict shape that LLM structured outputs and tool calls expect.

  • Free
  • No signup
  • Files stay on your device
Input Example JSON
JSON Schema
Paste an example of the data you want your AI agent to output, then click Generate.

Structured Outputs

This tool automatically sets additionalProperties: false and marks all fields as required, which is required for high-reliability features like OpenAI Structured Outputs.

How to use the JSON Schema Generator

A JSON Schema describes the structure of a JSON document: which fields exist, which type each one has, and which are required. APIs use it to validate requests, and LLM providers use it to force a model to answer in a fixed format. This generator reads a JSON sample and writes the schema in your browser.

  1. 1Paste an example of your JSON data.
  2. 2The generator infers types, properties, and required fields.
  3. 3Review the JSON Schema it produces.
  4. 4Copy it into your AI tool config, API validation, or docs.

Frequently asked questions

What does this generator do?

It reads a JSON sample and writes a JSON Schema for it, with the type of every field, nested objects and arrays, and a list of required properties.

Why use JSON Schema for AI and LLMs?

JSON Schema defines the exact structure you want a model to return, which is how features like structured outputs and tool or function calling enforce reliable, machine-readable responses instead of free-form text.

Is my JSON kept private?

Yes. The schema is generated locally in your browser, so your JSON data is never uploaded or stored anywhere.

Which JSON Schema draft does it output?

Draft-07. The generator marks every property as required and sets additionalProperties to false. OpenAI Structured Outputs and similar features need that strict shape.

Can I generate JSON from a schema instead?

Yes, with the Random JSON Generator on this site. Paste a JSON Schema there and it returns sample data that fits it.

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