Skip to the tools
All kits

JSON formatter

Paste JSON and format it, shrink it, or just check it. Nothing is uploaded.

When it does not parse, you get the line and the column with the offending character marked, which is the part most formatters leave you to work out.

Result

The result appears here.

Questions

Is what I paste sent anywhere?
No. Every tool in this kit runs in the page itself. There is no server here that receives what you paste, and you can check it in your browser's network tab: using a tool produces no request carrying your input at all.
How large a document can it take?
Five megabytes is comfortable and larger works. The parsing runs in a worker thread rather than in the page, so the tab stays responsive while it happens instead of freezing and looking crashed.
Why a line and column rather than the position the browser reports?
Because a character offset of 41,206 tells you nothing about where to look. The offset is converted to a line and a column and the line itself is quoted back with a caret under the character, the way a compiler does it.
Does formatting change my data?
Only its whitespace. The document is parsed and written back out, so key order is preserved and values are untouched. One thing to know: JSON has no comments and no trailing commas, so a file with either is not JSON and will be reported as invalid rather than silently repaired.
Are very large numbers safe?
Not entirely, and that is JSON's problem rather than this tool's. JavaScript numbers lose precision above about 9 quadrillion, so an integer larger than that comes back rounded. If your document carries large ids, keep them as strings.

The other tools here