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Visual JSON Schema Builder

Compose a JSON Schema (Draft 2020-12) with a tree editor, watch the JSON build live, then test a JSON instance against what you built — validation runs here in the browser.

Schema tree

{"type":"object","title":"Person","prope
{"type":"string","title":"name","minLeng
{"type":"string","title":"email","format
{"type":"integer","title":"age","minimum
{"type":"array","title":"tags","items":{
{"type":"string"}
New properties default to a required-less string.

Generated schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "title": "Person",
  "properties": {
    "name": {
      "type": "string",
      "title": "name",
      "minLength": 1
    },
    "email": {
      "type": "string",
      "title": "email",
      "format": "email"
    },
    "age": {
      "type": "integer",
      "title": "age",
      "minimum": 0,
      "maximum": 150
    },
    "tags": {
      "type": "array",
      "title": "tags",
      "items": {
        "type": "string"
      }
    }
  },
  "required": [
    "name"
  ],
  "additionalProperties": true
}

Validate a JSON instance

Result

✓ Valid — the instance satisfies every constraint in the schema.

About this tool

Build a Draft 2020-12 JSON Schema from a tree of objects, arrays and scalar types, or paste an existing schema and edit it. The validator implements the core keyword set itself — type, required, enum, const, numeric range, string length/pattern/format, array bounds and $ref resolution — and reports errors by JSON path. Everything runs locally in your browser; nothing is uploaded. Validation is capped at 200 errors and 40 levels deep to keep the tab responsive.

  • 100% free — no account needed
  • Runs in your browser
  • Nothing is uploaded

Frequently asked questions

Is Visual JSON Schema Builder really free?

Yes. Visual JSON Schema Builder is completely free on PureBrowser — every feature, with no account, no trial, and no credit card.

Does Visual JSON Schema Builder upload my data?

No. Visual JSON Schema Builder runs entirely inside your browser, so anything you type, paste, or open stays on your own device.

Do I need to sign up or install anything?

Neither. There is no account and nothing to download — open the page and Visual JSON Schema Builder is ready to use on desktop or mobile.

Does Visual JSON Schema Builder work offline?

Once the page has loaded, yes. All of the processing happens locally in your browser, so it keeps working without a connection.

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