JSON Formatter & Validator

Pretty-print, minify, and validate JSON.

What does this tool do?

JSON (JavaScript Object Notation) is the standard data format for APIs and config files, but minified or hand-written JSON is often hard to read. This tool parses your JSON, checks that it's valid, and lets you either pretty-print it with consistent indentation or minify it down to a single compact line, useful when debugging an API response or shrinking a payload before sending it.

How to use this tool

Paste your JSON into the input box, then click Format / Beautify to indent it, Minify to compress it, or Validate to just check it's well-formed without changing anything. If the JSON is invalid, the error message will describe what's wrong. Everything runs locally in your browser; nothing is uploaded anywhere.

Common use cases

  • Pretty-printing a minified API response to actually read it while debugging.
  • Minifying a config file or payload before sending it, to shrink its size.
  • Validating hand-written or generated JSON before committing it to a config file or database column.
  • Checking whether a third-party API's response is well-formed before writing a parser against it.

Frequently asked questions

What counts as invalid JSON?

Common issues include trailing commas, single quotes instead of double quotes, unquoted object keys, and missing brackets or braces. JavaScript object literals often look like JSON but aren't strictly valid JSON for exactly these reasons.

Does minifying change the data, only the formatting?

Only formatting. Minify removes whitespace and line breaks between tokens; the underlying keys, values, and structure are untouched, and the result parses back to the exact same data.

Is my JSON uploaded anywhere?

No. Parsing, formatting, and validation all happen locally in your browser using the built-in JSON.parse()/JSON.stringify(); nothing is sent to a server.

Can this handle very large JSON files?

It can handle anything your browser's JavaScript engine can parse in memory, typically tens of megabytes without issue, though extremely large files may feel sluggish since parsing happens on the main thread.