JSON Formatter & Validator
Paste JSON below and format it into readable, indented text, compress it to a single line, or check whether it is valid — all in your browser.
Runs locally in your browser. Nothing is uploaded.
What is a JSON formatter?
JSON (JavaScript Object Notation) is the standard format for data exchanged between web services, configuration files, and APIs. It is compact by design, which makes raw JSON hard to read: everything may sit on one long line, with nested objects and arrays buried inside each other. A JSON formatter takes that compact text and re-indents it, putting each key, value, and bracket on its own line so the structure becomes visible at a glance. The companion operation, minifying, does the reverse — it strips all unnecessary whitespace and squeezes the data back onto a single line, which is useful when pasting JSON into a URL parameter, a config field, or a compact request body.
This tool also validates. JSON has strict rules: keys must be double-quoted, trailing commas are not allowed, comments are not allowed, and single quotes are not a substitute for double quotes. Text copied out of JavaScript source code often breaks one of these rules, so a validator that points at the exact spot of the problem saves a lot of hunting. When parsing fails, this tool reports the browser’s error message and, when a character position is available, converts it into a line and column number you can jump to in the input.
How to use the JSON formatter
First, paste your JSON into the input box. Choose an indent size of 2 or 4 spaces, then click Format to pretty-print it, or Minify to compress it to one line. The result appears in the output box, where you can review it and copy it with the Copy result button. If you only want to check validity without changing anything, click Validate: it reports whether the JSON is legal and what its top-level type is (object, array, string, number, or null). The Load sample button fills in a small example so you can try the tool before pasting your own data, and Clear resets both boxes.
Frequently asked questions
How accurate is the reported error position?
The message comes from your browser’s JSON parser, and different browsers phrase it slightly differently. When a character position is included, this tool converts it to a line and column for you. If your browser only reports a line, use that line as the starting point and scan nearby characters.
Why did a long number change after formatting?
JSON numbers are parsed by JavaScript as floating-point values, so integers longer than about 15–16 digits can lose precision. IDs such as 19-digit order numbers should be stored as quoted strings in the source data. Once precision is lost, no formatter can recover the original digits — the fix belongs at the data source.
How large a document can I format?
Everything runs locally in your browser, so documents of a few megabytes format instantly. Very large files (tens of megabytes) may briefly slow the page; for those, a dedicated code editor is a better choice.
Is my JSON sent anywhere?
No. Parsing and formatting happen entirely on your device. Nothing leaves the page, and no data is stored.
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JSON Repair · JSON Diff · JSON to CSV / CSV to JSON · Hash Generator