JSON Formatter & Schema Validator

JSON Formatter & Schema Validator

What It Is

This tool formats, minifies, and validates JSON documents, with a separate schema validation mode that checks JSON payloads against JSON Schema Draft 07 and 2020-12 definitions. Developers use it for debugging API responses, validating configuration files, ensuring data integrity before processing, and catching structural errors that would otherwise surface at runtime.

How It Works

The formatter uses JSON.parse() to validate syntax, then JSON.stringify(parsed, null, indent) to produce prettified output. Minification uses the same approach with no whitespace.

Worked Example

Input (unformatted): {"name":"John","age":30,"city":"New York"}. Format output (2-space indent):

{
  "name": "John",
  "age": 30,
  "city": "New York"
}

Schema validation example: The validator checks the JSON payload against the schema definition, returning any validation errors found.

Common Mistakes

• Trailing commas. JSON does not allow a comma after the last property.
• Unquoted or single-quoted keys. JSON requires double-quoted property names.
• Mixing JSON Schema drafts. Draft 2020-12 moved tuple validation from items to prefixItems.