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Format messy JSON into clean, readable output, minify it back down, or just validate it — with a plain-language error message when something's wrong instead of a cryptic failure. Built for developers, and for anyone an API has ever sent a wall of unformatted text.
JSON is the world's default data hand-off format — APIs, configuration files, app storage and logs all speak it. It's also routinely delivered in the least readable form possible: one enormous line, no indentation, thousands of characters deep. Humans can't debug what they can't scan. Formatting (or “beautifying”) restructures the same data with line breaks and indentation so nesting becomes visible at a glance: which keys belong to which object, where an array opens and closes, whether a value is a string, a number or a boolean.
The other half of the job is validation. JSON's rules are simple but unforgiving — one trailing comma, one set of single quotes, one unquoted key, and the whole document is invalid. Parsers in production code often fail silently or with useless messages. This tool tells you not just that your JSON is broken but where, so you can fix the actual character at fault instead of proofreading 4,000 lines by eye. And when you're done reading, Minify compresses it back to the compact form machines prefer — smaller payloads, faster transfers.
An API returns this single line:
{"user":{"id":4815,"name":"Sara","roles":["admin","editor"],"prefs":{"theme":"dark","alerts":true}}}
Formatted with 2-space indentation, the same data becomes a tidy tree: user opens, and inside it id, name, the roles array with its two entries on separate lines, and the nested prefs object — structure you can verify in seconds. Nothing about the data changed; only its readability did. Then suppose the original had a trailing comma after true. Instead of a mystery failure, the validator flags a syntax error at that position — delete the comma, re-run, done.
{name: "Sara"} is a JavaScript object, not JSON.} where a ] belongs, usually after hand-editing a long file.NaN, undefined or Infinity, which JSON doesn't recognize.Formatting restructures valid JSON so it's easy to read. Validating only answers one question — is this legal JSON or not — and points at the error if it isn't. Formatting a document also validates it; invalid JSON can't be formatted.
Because JSON is stricter than JavaScript. Keys must be double-quoted, strings must use double quotes, and trailing commas and comments aren't allowed. The error message will point at the first place your input breaks a JSON rule.
No. Whitespace between tokens isn't data. The formatted and minified versions contain exactly the same keys, values and structure — parse either one and you get identical data back.
No. Parsing and formatting happen in your browser with JavaScript. You can safely format payloads containing private or internal data — though you should still treat real credentials with care everywhere.
Two spaces is the most widely used convention in web APIs and tooling, and keeps wide documents on screen. Four spaces is easier for some readers. Tabs let every viewer set their own visual width. There's no wrong answer — consistency matters more than the choice.
Yes, within reason — multi-megabyte documents format fine on a modern device, since everything is processed locally. Extremely deep nesting may become hard to read rather than hard to process; the validator will still check it.