JSON formatter & validator
Paste JSON to pretty-print or minify it, find the exact line of a syntax error, sort keys, or convert to and from CSV. Nothing leaves your browser.
Runs entirely in your browser. Nothing you enter is sent to a server.
Shortcuts
Common JSON errors
- Trailing commas —
{"a":1,}isn’t valid JSON, even though JavaScript allows it. - Single quotes — strings and keys must use double quotes.
- Unquoted keys —
{a:1}must be{"a":1}. - Comments — standard JSON has no comments. Remove
//and/* */lines. - NaN, Infinity, undefined — not allowed; use
nullor a string.
The validator shows the line and column of the first error and highlights it in the input.
Working with an API? Decode a Base64 payload or JWT with the encoder/decoder, convert created_at numbers with the timestamp converter, or generate test IDs with the UUID generator.
Frequently asked questions
Is my JSON sent to a server?
No. Parsing and formatting happen in your browser with the built-in JSON parser.
How large a file can it handle?
Several megabytes is fine on most devices. Very large files (100 MB+) may be slow because everything is held in memory.
Does sorting keys change my data?
No. It only reorders object keys alphabetically; array order is preserved.