JSON format, beautify, minify & side-by-side diff
JSON (JavaScript Object Notation) is the most common data format for web APIs, configuration files, and service-to-service data exchange. This online JSON formatter beautifies minified JSON, validates syntax, minifies for production payloads, and compares two JSON documents side-by-side.
Everything runs locally in your browser — your data is never uploaded to any server. You can verify this by opening the Network tab in your browser DevTools while using the tool.
{"name":"Alice","age":30,"hobbies":["coding","music"]}{
"name": "Alice",
"age": 30,
"hobbies": [
"coding",
"music"
]
}{
"id": 1,
"active": true
}{"id":1,"active":true}No. All formatting, validation, and diff comparison runs entirely in your browser using JavaScript. We don't log, store, or transmit your input.
There's no hard limit, but performance depends on your device. Most browsers handle 10MB+ JSON files smoothly. Files over 50MB may cause noticeable lag during formatting.
This usually means the JSON is invalid. Common causes: trailing commas, unquoted keys, or single quotes around strings. Strict JSON requires double quotes and forbids trailing commas.
No. This tool follows the strict JSON spec (RFC 8259), so comments and trailing commas are rejected. For lenient parsing, use a JSON5-specific tool.
The diff is structural: it compares values by JSON path, so key order doesn't matter. {"a":1,"b":2} and {"b":2,"a":1} are considered identical, unlike a text diff.