Format and validate JSON
Pretty-print JSON and catch syntax errors, entirely in your browser.
What to know
The text is parsed with the browser's own JSON parser, then printed with two-space indentation. Because it is a real parse rather than a text reformat, invalid JSON is reported instead of being silently mangled.
Parsing locally matters more than it might seem: API responses routinely contain access tokens, customer records and internal identifiers. Pasting those into a server-side formatter hands them to a third party.
Questions
Is anything uploaded to a server?
No. Every tool on this site runs inside your browser using standard web APIs. There is no upload, no account, no logging and no server holding your data afterwards. You can confirm it by opening your browser's developer tools and watching the network tab stay empty while you work.
Why does it say my JSON is invalid?
Common causes are trailing commas, single quotes instead of double, unquoted keys, and comments — all valid JavaScript but none valid JSON. The error message gives the character position.