JSON Formatter, Validator And Viewer

JSON arrives in a state. An API returns it on one enormous line, a config file has been hand-edited by four people, a model hands you a block that looks right and will not parse. Paste it here and the tool does the obvious thing: indent it with the spacing you want, say precisely where it is broken if it is, and give you a tree you can fold up so a long response fits on one screen. It is a JSON formatter, a JSON validator and a JSON viewer in one panel, with a Minified tab for when you want the file back on a diet.

The Error Message You Actually Wanted

Browsers report broken JSON very differently: one says “position 412”, another says “line 12 column 9”, and one just says it expected a closing brace. This tool takes whichever it gets, works out the exact line and column, prints that line with a caret under the offending character, and adds a plain-English note when the mistake is a familiar one. A trailing comma, a single-quoted key, a stray NaN, Python's True, a comment, a curly quote from a word processor, two records pasted where one value belongs: each gets named rather than hinted at. For the two faults behind most failures - a trailing comma and single quotes - the “Repair the obvious” button fixes them and then says exactly what it changed. It never edits your text on its own.

Who It Is For

You do not have to be a developer. If you are checking a webhook payload, opening an export from a tool that promised “JSON”, or working out what an AI assistant handed you, this does the reading for you. The tree view shows each key with its type and, for objects and arrays, how many children it has, so you see the shape before the values. Large arrays stay folded and say how many items they hold rather than rendering thousands of rows.

How It Works, And Its Limits

Everything runs in your browser. Nothing is uploaded, nothing is stored, and the tool never evaluates what you paste. That also sets the limits: strict JSON only, so comments and trailing commas are errors rather than features (the repair button aside), file size is bounded by your device's memory, and numbers keep JavaScript precision, so an ID longer than sixteen digits can lose its last few. If your data started as a spreadsheet, CSV to JSON is the better first stop, and the HTML formatter handles markup the way this handles data.

Then Put It On A Link

When you need to show someone the payload rather than paste it into a chat, the publish button puts a colour-coded page of your JSON on a free OxyPages subdomain with HTTPS, in seconds, without an account. The link lasts 30 minutes; claiming it is free, keeps it permanently and lets you pick the address, with custom domains available on paid plans. Instant publishing accepts up to 5 MB. See how it works or compare plans.