JSON Formatter

Format and validate JSON

Paste a JSON document and select Format JSON to check its syntax and render it with two-space indentation. Formatting runs in your browser, with no account or file upload required.

The input remains editable, and a successful result appears in a separate, read-only output field. Use Copy to copy the formatted result or Clear to reset the tool.

Example

Input:

{ "name": "ToolsVault", "active": true, "items": [1, 2] }

Formatted output:

{
  "name": "ToolsVault",
  "active": true,
  "items": [1, 2]
}

This makes nested objects and arrays easier to inspect when reviewing API responses or application configuration.

How to use it

1. Paste JSON into the input field.
2. Select Format JSON.
3. If the input is valid, review the formatted output and copy it.
4. If an error is shown, correct the input and select Format JSON again.

Conversion happens when you select the button. Editing the input does not automatically refresh an earlier result.

Common syntax errors

Single quotes or unquoted keys

JSON requires double quotes around property names and string values. Use {"name":"Alice"} rather than JavaScript object syntax such as {name:'Alice'}.

Trailing commas

A comma after the final object member or array element is invalid JSON. Remove the final comma before the closing bracket.

Comments

Standard JSON does not allow line or block comments. Remove comments from configuration snippets before validating them.

Incomplete input

Check that quotes, braces and brackets are paired. The current tool shows a general error for invalid JSON; it does not locate a specific line or repair the input automatically.

Limits and numeric values

The formatter uses JavaScript's JSON parser and produces two-space indentation. It does not currently provide compression mode, custom indentation or syntax highlighting.

Very large documents depend on your browser's available memory. Large integer identifiers may exceed JavaScript's exact numeric range; when an ID must remain exact, use a quoted string if the data format permits it and verify the result before reuse.

Nested data and a ready-made example

The example button fills an object containing a nested array, null, a boolean, and a Unicode string. Click Format JSON after loading it; the example is input, not an automatically generated result. For {"rows":[{"id":1,"note":null}],"active":true}, the same values and nesting should remain after formatting.

Formatting parses and serializes the data. It is not byte-preserving: whitespace changes, repeated object keys can collapse to the last value, and numbers use JavaScript numeric precision. Keep the original when exact source bytes or duplicate-key evidence matters.

Continue with your data

For delimited tables, open the CSV viewer. To review changes between two JSON responses after formatting them, use text diff.