JSON Formatter

Validation results you can act on

Validation runs on every keystroke. When the JSON is valid you get live counts of objects, arrays, keys and depth. When it is not, the error is reported with its exact line and column, the probable cause, and a highlight at the failing position in the editor — not just "Invalid JSON".

Common JSON errors this tool pinpoints

These four mistakes account for most invalid JSON. Each one is detected with a position and a probable cause:

Before / After

Minified API response on the left, the same data formatted with 2-space indent on the right. Structure, tree and paths update from the parsed document.

{"user":{"id":123,"name":"Chen","roles":["admin","editor"],"active":true}}

{
  "user": {
    "id": 123,
    "name": "Chen",
    "roles": [
      "admin",
      "editor"
    ],
    "active": true
  }
}

JSON standard quick reference (RFC 8259)

• Two structures: an object (unordered name/value pairs, {}) and an array (ordered values, []).
• A value is a string in double quotes, a number, true, false, null, an object, or an array.
• Numbers never have leading zeros; 1E10 and 0.5e-2 exponent forms are allowed.
• Strings may not contain literal control characters — they must be escaped (\n, \t, \uXXXX).
• No comments, no trailing commas, no single quotes — the strict grammar is what makes JSON portable.

Next steps with this data

Formatting is the first step. Continue the workflow without leaving your browser: