Format and validate JSON without uploading it

Nobody formats invented JSON. They format the response that just came back wrong, from staging or from production, and it is full of real records belonging to real people. Pasting that into a hosted formatter is a data transfer with no basis behind it, and if the payload happens to include a bearer token or an API key in a field, it is also a credential disclosure.

What formatting gives you is a structural verdict. If it will not parse, the usual causes are dull and specific: a truncated copy that lost its closing brackets, a trailing comma, or curly quotes picked up by copying out of a document rather than a terminal. Indented output then makes the shape of the response obvious in a way a single line never does.

Read what you have before it goes anywhere else. A formatted payload is much easier to paste into a ticket or a chat, which is how production records end up in an issue tracker that outlives the incident. Cut the payload down to the fields that demonstrate the problem and replace the identifiers before you share it.

The verification is direct: open the network panel, paste a payload, format it, and watch that no request is made. Or disconnect first, because parsing and re-printing text needs nothing but your own machine, and the tool carries on working while a hosted equivalent stops dead.