JSON Validator Online — Schema Validation with Ajv

Catch syntax errors instantly with line and column markers. Paste a JSON Schema to validate complex documents using Ajv with format checks (date-time, email, uri, ipv4, ipv6, uuid, regex…). Runs entirely in your browser.

Open JSON Validator →

How JSON Schema validation works here

  1. Open the editor and paste your JSON.
  2. Open the side panel (⌘ \) and choose the Schema tab.
  3. Paste a JSON Schema. The active document is continuously validated; errors appear with their instancePath.

Example schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "required": ["name", "email"],
  "properties": {
    "name":  { "type": "string", "minLength": 1 },
    "email": { "type": "string", "format": "email" },
    "age":   { "type": "integer", "minimum": 0 }
  }
}

Ajv-powered

Industry-standard JSON Schema validator with full format support.

Inline errors

Source-mapped lint markers in the text view with line + column.

Path-aware

Errors carry instancePath so you can jump to the offending node.

Lazy-loaded

Ajv loads only when you open the schema tab — no overhead otherwise.

Local-first

Runs in a Web Worker. Your schema and document never leave your device.

Free forever

No signup, no paywall, works offline.

Frequently Asked Questions

How does JSON Schema validation work?

Open the side panel, paste your JSON Schema, and the active document is continuously validated. Errors will appear instantly with their line, column, and instance path.

Which validator engine is used?

We use Ajv (Another JSON Schema Validator), an industry-standard validation engine that fully supports the latest JSON Schema drafts and custom format checks.

Does the validation check format types?

Yes, it fully supports string formats like email, uri, date-time, ipv4, ipv6, uuid, and regular expressions.