Paste JSON and it is parsed with the strict RFC 8259 grammar, then rewritten with 2 spaces, 4 spaces, tabs or no whitespace at all. For example, { "a" : [ 1 , 2 ] } minifies to {"a":[1,2]}, 11 characters. Invalid input, such as a trailing comma, is reported with its line and column.
API responses, log lines and config files often arrive as one long line of JSON that nobody can read. This formatter parses the text with the same strict grammar every browser uses, then prints it back with the indentation you pick, or squeezes it onto a single line for a request body. An option sorts every object's keys alphabetically, which turns two differently ordered payloads into text a diff tool can compare. Alongside the output it counts objects, arrays, keys, scalar values and nesting depth, so you can see the shape of a payload at a glance. It does not accept JSON5 or JavaScript extras: comments, single quotes and trailing commas are errors. Very large numbers beyond about 15 significant digits lose precision when parsed, as they do in any JavaScript program.
Paste into the box or open a .json or .txt file from your device; it is read locally.
Choose 2 spaces, 4 spaces, tabs, or Minify for a single line with no whitespace.
Tick the sort option to order every object's keys alphabetically at all levels.
Use Copy result to take the formatted text, or read the error message to find a syntax problem.
Result Formatted JSON: {"a":[1,2]}
Objects: 1
Arrays: 1
Keys: 1
Scalar values: 2
Nesting depth: 2
Output lines: 1
Input characters: 19
Output characters: 11
All whitespace between tokens is dropped, leaving 11 characters with the same meaning.
Result Formatted JSON: {
"alpha": {
"b": null,
"y": true
},
"mid": [
1,
2,
3
],
"zeta": 1
}
Objects: 2
Arrays: 1
Keys: 5
Scalar values: 6
Nesting depth: 2
Output lines: 12
Input characters: 52
Output characters: 128
Keys come out as alpha, mid, zeta at the top level and b before y inside alpha, which makes two versions of a config easy to diff.
output = serialise(parse(input), indent), with keys optionally sorted before serialising
parseindentdepthThe text is parsed into values first, so formatting never changes the data: strings keep their escapes, numbers keep their value, and whitespace between tokens is simply discarded. Serialising then writes one member per line at the chosen indent. When a parse fails, the position reported by the parser is converted into a line and column.
No. The JSON is parsed into values and written back out, so only whitespace changes. The one exception is very long integers: numbers beyond about 15 significant digits are stored as double-precision floats and may lose their last digits.
RFC 8259 leaves duplicate keys undefined. The parser here keeps the last value for a repeated key, so the formatted output contains that key once.
Many editors read JSONC or JSON5, which allow comments, single quotes and trailing commas. Strict JSON allows none of those. The error message gives the line and column where parsing stopped.
For JSON data it is: object members have no defined order in the specification, so sorting does not change meaning. Array order is kept as it is, because arrays are ordered.
The top-level value is level 0 and each object or array adds one level for its contents. {"a":[1,2]} has depth 2 because the numbers sit inside an array inside an object.
No. Parsing and formatting run in your browser, including when you open a file, so API keys or personal data in the payload stay on your device.
Using this tool in an assignment, article or report? Copy a citation, or a link for your website.
Tools Directory Editorial Team. (2026, October 28). JSON Formatter. Tools Directory. Retrieved October 28, 2026, from https://tools.milunir.com/developer-tools/json-tools/json-formatter/
Tools Directory Editorial Team. “JSON Formatter.” Tools Directory, 28 Oct. 2026, https://tools.milunir.com/developer-tools/json-tools/json-formatter/. Accessed 28 Oct. 2026.
Tools Directory Editorial Team. “JSON Formatter.” Tools Directory. Last modified October 28, 2026. Accessed October 28, 2026. https://tools.milunir.com/developer-tools/json-tools/json-formatter/.
<a href="https://tools.milunir.com/developer-tools/json-tools/json-formatter/">JSON Formatter – Tools Directory</a>