JSON Formatter & Validator

What is JSON formatting?

JSON formatting (pretty-printing) converts compact, single-line JSON into an indented structure that humans can scan. When you receive a raw API response like {"user":{"id":1,"roles":["admin"]}}, a formatter turns it into:

{
  "user": {
    "id": 1,
    "roles": ["admin"]
  }
}

When to format vs. minify

• Format — while debugging API responses, editing config files (tsconfig.json, package.json), or reviewing data in development.
• Minify — before shipping JSON in production APIs. Removes all whitespace, reducing payload size by 10–30%.

Common JSON syntax errors

The validator catches these before they cause runtime failures:

• Trailing commas — ["a", "b",] is valid JS, not valid JSON
• Single-quoted strings — JSON requires double quotes on both keys and values
• Unquoted keys — {name: "Alice"} is JavaScript object syntax, not JSON
• Comments — JSON has no // comment syntax unlike JSONC or JSON5
• Missing commas between properties or array elements

How do I format JSON online?

Paste your JSON into the input field and it automatically validates and formats it in real time. You can choose between 2-space, 4-space, or tab indentation. Click Format to apply the formatting to the input field.

Does this tool upload my JSON data?

No. All formatting, validation, and minification happens entirely in your browser using JavaScript. No data is ever sent to a server. This makes it safe for API responses, config files, and sensitive data.

What does the JSON minifier do?

The minifier removes all unnecessary whitespace, newlines, and indentation from your JSON, producing the smallest possible valid JSON string. Useful for reducing payload size in APIs and storage.

Can it detect JSON syntax errors?

Yes. The tool validates JSON as you type and shows detailed error messages including the approximate line number where the syntax error occurs.