Valid sample summary
The sample reports root object, five keys, three array items, depth two, and 88 UTF-8 bytes after compact serialization.
JSON VALIDATOR AND FORMATTER
Validate, format,
and minify JSON.
Check syntax, add indentation, create a one-line version, and inspect the root type, keys, array items, depth, and UTF-8 size.
Formatted result
Root type—
Total keys—
Array items—
Maximum depth—
UTF-8 size—
HOW TO USE
Format in three steps
- Paste a JSON value into the input.
- Choose two or four spaces for indentation.
- Format, minify, or copy the result.
EXAMPLES
Syntax and output checks
Trailing comma error
{"a":1,} is not standard JSON. Remove the comma before the closing brace.
Format versus minify
Two-space, four-space, and compact output preserve parsed values while changing whitespace only.
Local processing
No external API is needed to parse or format the input.
Standard browser JavaScript performs all operations on this device.
How validation works
The tool parses standard JSON in browser memory and serializes the same data structure again.
Only standard JSON is accepted
Keys and strings require double quotes. Comments, single quotes, trailing commas, JSON5, and JavaScript object syntax are not supported.
Formatting does not change values
Prettifying and minifying only change whitespace around a successfully parsed structure.
Protect sensitive and large data
Input is not sent by this page, but screen sharing and extensions are separate risks. Very large JSON can be slow on limited devices.
Scope and limitations
Only standard JSON is accepted. Comments, single quotes, trailing commas, JSON5, schema validation, and file upload are unsupported. Large or deeply nested values depend on browser memory and recursion depth, and duplicate keys receive no separate warning.
JSON formatter FAQ
Is syntax validation the same as schema validation?
No. This tool checks grammar, not required fields or semantic rules.
Why can the byte count differ from the source?
The summary measures the compact reserialized JSON, without source whitespace.
Are duplicate keys reported?
No. They follow browser JSON.parse behavior without a separate warning.
Can I upload a JSON file?
No. Paste text into the editor.