JSON Formatter and Validator

There is no Run button. The result updates as you type or paste, so you can adjust the settings and watch the output change.

1. Paste your JSON into the Input box, or press Paste to read it from the clipboard. Try it loads a small example.
2. Set Mode to Beautify for one key or array item per line, or to Minify for a single line with no spaces outside strings.
3. Choose the Indent: 2 spaces, 4 spaces or Tab. It only affects Beautify.
4. Tick Sort object keys if you want every object ordered alphabetically, at every depth.
5. Read the status line under the boxes. It says "Valid JSON" with the total number of keys and the top-level type, or "Invalid JSON" followed by the parser message.
6. Press Copy or Download .txt. Use as input moves the result back into the input box, so you can minify a document you have just sorted.

Parsing is done by your browser's own JSON engine, so the text never leaves the page. That makes it reasonable to inspect API responses and configuration files that contain tokens.

The tool parses the text into values and writes it out again, rather than just adjusting spaces. That is why invalid input produces no output, and why a few details are normalised. Take {"a":1,"b":[true,null]}: Beautify with 2 spaces puts every key and array item on its own line, and Minify returns the original single line. Because the text is rewritten, expect these changes:

• Numbers are printed in their shortest form, so 1.0 becomes 1 and 1e2 becomes 100.
• Escapes are normalised: "é" becomes "é" and "\/" becomes "/".
• If a key appears twice in one object, only the last value survives.
• Integers above 9,007,199,254,740,991 lose digits: 12345678901234567890 comes back as 12345678901234567000. Keep identifiers that long as strings in the source.
• Key order is kept as written unless Sort object keys is ticked.

Sorting is recursive. {"b":1,"a":{"z":1,"c":[3,1]}} comes out with a before b and c before z, while the array [3,1] keeps its order, because position inside an array carries meaning. Sorted output pairs well with the diff checker when you compare two exports.

When parsing stops, the status line shows the message from your browser's JSON parser, and the wording differs between Chrome, Firefox and Safari. In Chromium-based browsers it also gives a line and column, for example column 8 for {"a":1,}. That position is where the parser gave up, which is usually at or just after the real mistake. Most failures come from habits carried over from JavaScript or Python:

Smart quotes pasted from a word processor and Python values such as True or None fail in the same way. A JSON Lines file, with one object per line, is not one valid document, so check it a line at a time.

The checker looks at syntax only. It does not compare a document with a JSON Schema, so a missing field or a string where you expected a number still counts as valid. Files that allow comments, such as tsconfig.json or editor settings, fail until the comments are removed. The whole document is held in memory at once: a few megabytes is comfortable, tens of megabytes may make the tab sluggish. The download is named json-formatter.txt, so rename it to .json if you need that extension.

• To turn a document into a string you can paste inside code or another JSON value, use the JSON stringify text generator.
• For spreadsheet data, the CSV to JSON converter works in both directions.
• Configuration that people edit by hand is often easier to read as YAML, and the YAML to JSON converter translates between the two.
• To read the payload inside a login token, paste it into the JWT decoder.