JSON Formatter & Validator
Prettify, validate and minify JSON instantly in your browser.
Files are processed in memory and never stored.
Paste messy or minified JSON and get it cleanly indented and validated in real time. Catch a misplaced comma or unquoted key the moment it happens, then copy the formatted result. Everything runs locally in your browser — your data is never sent anywhere.
How to use it
- Open the JSON Formatter and paste your JSON.
- Pick an indent (2 or 4 spaces) or choose Minify.
- If the JSON is invalid, the error tells you what's wrong.
- Copy the formatted output.
Why format JSON
JSON is the lingua franca of APIs and config files, but raw responses are often minified into a single unreadable line. Formatting adds consistent indentation and line breaks so you can actually see the structure — which object contains which field, where an array begins and ends, and whether a value is a string or a number.
Validation matters just as much. A single trailing comma or an unescaped quote will break a parser, and the error messages from production systems are rarely helpful. Formatting and validating before you paste JSON into code or a ticket saves a surprising amount of debugging time.
Pretty-print vs. minify
Pretty-printing expands JSON for humans; minifying strips every optional space and newline for machines. Use a pretty 2- or 4-space layout while you're reading or editing, and minify when you need the smallest possible payload to embed in a URL, a config value, or an API request.
Frequently asked questions
Is my JSON sent to a server?
No. The formatter runs entirely in your browser — nothing is uploaded or stored.
What does 'invalid JSON' mean?
Your text isn't valid JSON — usually a trailing comma, a missing quote, or a stray character. The error message points to the problem.
Can it handle large JSON?
Yes, within your browser's memory. Very large documents (tens of megabytes) may format more slowly.
Does it change my data?
No. Formatting only changes whitespace; minifying removes whitespace. The actual values are never altered.
Why use this over an extension?
No install, no permissions, and it works on any device with a browser.
Is it free?
Yes — free, no sign-up, no limits.