Validation Schema Generator

Infer a JSON Schema (Draft-07 or 2020-12) from a sample JSON document, with options for required fields, titles, examples and additionalProperties.

JSON example500 chars / 30 lines

Generated JSON Schema1,479 chars / 85 lines

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "id": {
      "type": "integer"},
    "name": {
      "type": "string"},
    "version": {
      "type": "string"},
    "active": {
      "type": "boolean"},
    "rating": {
      "type": "number"},
    "tags": {
      "type": "array",
      "items": {
        "type": "string"}
    },
    "metadata": {
      "type": "object",
      "properties": {
        "created": {
          "type": "string"},
        "author": {
          "type": "string"},
        "downloads": {
          "type": "integer"}
      },
      "required": [
        "created",
        "author",
        "downloads"],
      "additionalProperties": false
    },
    "features": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string"},
          "category": {
            "type": "string"},
          "premium": {
            "type": "boolean"}
        },
        "required": [
          "name",
          "category",
          "premium"],
        "additionalProperties": false
      }
    },
    "config": {
      "type": "null"}
  },
  "required": [
    "id",
    "name",
    "version",
    "active",
    "rating",
    "tags",
    "metadata",
    "features",
    "config"],
  "additionalProperties": false
}

Valid JSON Schema (Draft-07)9 properties

How it works

Type detection

Detects string, number, integer, boolean, null, array, and object types automatically.

Nested objects

Recursively generates schemas for deeply nested objects and arrays of objects.

Mixed arrays

Handles arrays with mixed types using anyOf. Detects homogeneous arrays for cleaner schemas.

Edge cases

Handles empty arrays, null values, and distinguishes between integer and floating-point numbers.

Updated October 2, 2026. Provided as is. Check the output before you rely on it in production.

How to use Validation Schema Generator

1

Paste a representative example

Paste a JSON object that reflects the data you need to validate, including optional fields.
2

Pick the schema draft

Choose the JSON Schema draft your validation library expects.
3

Review the inferred types

Check detected types, nested object schemas and mixed arrays before you rely on the schema.
4

Copy and tighten

Copy the schema into your project and add constraints such as required fields, enums and string patterns.

Questions and answers

What is Validation Schema Generator?

A JSON Schema describes the expected shape of JSON data, its types, required fields and nesting, so validators can reject bad input. This tool infers one from a representative example, in Draft-07 or 2020-12, with toggles for required fields, titles and examples. It uses the same engine as JSON Schema Generator.

Which validators can use the output?

Any JSON Schema validator, such as Ajv in JavaScript or jsonschema in Python, plus AI APIs that accept JSON Schema for tool parameters and structured output.

Is my data uploaded?

No. Schema inference runs entirely in your browser.

For AI agents: how to call this tool

Machine-readable contract, endpoints and examples. Humans can ignore this section.

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/validation-schema-generator/

For automation planning, fetch the canonical contract at /api/tool/validation-schema-generator.json.

Validation Schema Generator