Beautify messy JSON, catch syntax errors, or minify for production. Everything runs in your browser — your JSON never leaves your device.
[1, 2, 3,] is not valid JSON, although most programming languages accept it.{name: "Atle"} is valid JavaScript but invalid JSON.// and /* */ before parsing.Is my JSON sent to a server?
No. Everything runs in your browser using native JSON.parse and JSON.stringify.
Nothing is transmitted to us and nothing is stored. The page even works offline after the first load.
What's the difference between beautify and minify?
Beautify adds indentation and line breaks for readability. Minify strips whitespace so the JSON is smaller to send over the wire. Both produce semantically identical output — parsers treat them the same.
Why does my JSON fail to validate?
Usually trailing commas, single quotes, unquoted keys, or comments. JSON is stricter than JavaScript object literals. The error message below the input shows the exact position.
Does this support JSON5 or JSONC?
No — this validates strict RFC 8259 JSON. JSON5 (comments, trailing commas, unquoted keys) and JSONC (VS Code's JSON-with-comments) are not valid JSON and will fail parsing.
How big a file can it handle?
Roughly whatever fits in browser memory — tens of megabytes on desktop. Parsing is synchronous, so
extremely large payloads may briefly freeze the UI. For multi-gigabyte files, use a streaming parser
or a command-line tool like jq.