JSON Formatter
Paste JSON in the input box. It prints formatted, line by line, on the green bar. Errors print in ribbon red. Nothing leaves your browser.
Format, validate and minify JSON
Paste any JSON and it prints formatted with two-space indentation and syntax coloring. Invalid input prints the parser's message and, where the browser reports it, the position it failed at, so a missing comma is a one-second fix. Minify collapses everything to a single line for configs and API payloads; Sort keys orders every object alphabetically, recursively.
Everything runs in your browser. Large payloads never leave the tab, which makes this safe for real API responses.
What about JSON with comments?
Strict JSON has no comments. Lines starting with // are stripped before parsing so that config files still format.
Can it handle big files?
Yes. It is your machine doing the work; several megabytes format in well under a second.
Why green-bar paper?
Because formatted output is a printout, and line-printer paper is the most readable thing ever designed for long structured text: the half-inch bars keep your eye on the line.