JSON Formatter & Validator

Minified API responses and hand-edited config files are hard to read and easy to break. Paste JSON here and it is instantly validated and re-indented. If something is wrong, you get the error message with its line and column, so you can fix it in seconds. Choose Minified under JSON indent to compress it back into a single line.

1. Paste your JSON or drop a .json file into the input box.
2. Valid JSON is formatted immediately; invalid JSON shows an error with its position.
3. Change JSON indent in Options to 2 spaces, 4 spaces, tabs or Minified.
4. Copy the result or download it as a .json file.

Example

{"id":7,"tags":["a","b"],"meta":{"ok":true,"score":9.5}}

{
  "id": 7,
  "tags": [
    "a",
    "b"
  ],
  "meta": {
    "ok": true,
    "score": 9.5
  }
}

Formatting changes only whitespace: keys keep their order and every value stays exactly the same, so the formatted and minified versions are interchangeable.

The most common JSON errors

• Trailing commas: [1, 2, 3,] or {"a": 1,} are valid in JavaScript but not in JSON.
• Single quotes: strings and keys must use double quotes — 'name' is invalid.
• Unquoted keys: {name: "Sara"} must be {"name": "Sara"}.
• Comments: // … and /* … */ are not allowed in standard JSON.
• Special values: undefined, NaN and Infinity do not exist in JSON; use null or a string.
• Smart quotes: text copied from Word or chat apps may contain “curly quotes”, which are not valid delimiters.
• Missing brackets: an unclosed { or [ is reported at the end of the input.

Beautify or minify?

Formatted JSON with indentation is for humans: code reviews, debugging and documentation. Minified JSON removes all optional whitespace, which makes payloads smaller for APIs, local storage and configuration embedded in other files. Two-space indentation is the most common convention in JavaScript projects, four spaces in Python, and tabs in some Go and PHP code bases.

Very large numbers

JavaScript, and therefore every browser-based tool, stores numbers as 64-bit floating point. Integers longer than 15–16 digits — such as some database IDs or Twitter/X snowflake IDs — cannot be represented exactly and change when parsed. The formatter warns you when your JSON contains such numbers; the safe fix is to store them as strings.

Convert while you are here

Once your JSON is valid, switch the target format to turn it into something else: CSV, Excel, YAML, XML or JSON Lines.

Do it in code

For one-off files the tool above is quickest. To automate the same task in a script or pipeline, these snippets are a good starting point.

Python

# Pretty-print a file (Python 3.9+ also supports --compact to minify)
python -m json.tool data.json pretty.json --indent 2

Command line (jq)

jq . data.json            # format with 2-space indentation
jq -c . data.json         # minify to a single line

JavaScript

const pretty = JSON.stringify(JSON.parse(text), null, 2);
const minified = JSON.stringify(JSON.parse(text));

Frequently asked questions

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