json-formatter
// input
// output
// formatted output
About JSON Formatter
JSON Formatter is a free, client-side tool for formatting and validating JSON data. Paste any JSON string and instantly see it prettified with proper indentation, making deeply nested structures easy to read and debug. The formatter also validates syntax in real time — if your JSON is malformed, you get a clear error message pointing to exactly where the problem is.
Unlike online formatters that send your data to a server, this tool processes everything locally in your browser. API responses, config files, webhook payloads — none of it is logged or stored.
Developers use JSON formatters daily when working with REST APIs, debugging request bodies in Postman or Insomnia, reading AWS config outputs, or cleaning up minified JSON from production logs. This tool handles nested objects, arrays, Unicode strings, and large payloads without issue.
Use the Copy button to grab the formatted output, or clear the input to start fresh. The formatter uses 2-space indentation by default, matching the style of most editors and linters.
Frequently Asked Questions
Is my JSON data sent to a server? ▾
No. All formatting and validation happens in your browser using JavaScript's built-in JSON.parse() and JSON.stringify(). Your data never leaves your device.
Why does the formatter show an error on valid-looking JSON? ▾
JSON is strict about syntax. Common issues include trailing commas (not allowed in JSON, only in JavaScript), single-quoted strings (JSON requires double quotes), and unescaped special characters. The error message shows the exact position of the problem.
What's the difference between JSON and JavaScript objects? ▾
JSON is a text format for data exchange. It looks similar to JavaScript objects but has stricter rules: all keys must be double-quoted strings, values can only be strings, numbers, booleans, null, arrays, or objects — no functions, undefined, or Date objects.
Can I format minified JSON? ▾
Yes. Paste any minified one-liner and the formatter will expand it with proper indentation. This is useful for reading API responses, debugging compressed config files, or understanding production log output.
How do I validate JSON without formatting it? ▾
Paste your JSON and click Format. If it's valid, you'll see the prettified output. If there's a syntax error, you'll see an error message with the location. A clean format result confirms the JSON is valid.