Text tool

Format and validate JSON.

Paste anything and get it formatted, or get an error with the exact line and column instead of a vague complaint.

Free, no sign-up
Nothing is uploaded
No watermark, no limits

JSON formatter

Free

Paste JSON

Result

Formatted JSON appears here.

Indent with

Runs entirely in your browser. Nothing is uploaded.

Worth knowing

How to get this right.

01

The four things that break JSON
A trailing comma after the last item. Single quotes instead of double. Unquoted keys. A comment. All four are legal in JavaScript and none are legal in JSON, which is why hand-edited config files break so often. The error above gives you a line and column so you can go straight to it.
02

Minify for the wire, format for people
Minified JSON saves real bytes on an API response. Formatted JSON saves real minutes when something goes wrong. Store and edit the formatted version; serve the minified one — and if it is going over HTTP, gzip closes most of the gap anyway.
03

Depth is a design smell
The result panel reports nesting depth. Past four or five levels, most consumers of your JSON will be writing defensive code to walk it. That is usually a sign the shape wants flattening, not that the reader needs to try harder.

Questions

About this tool.

Is my JSON sent anywhere?

No. Parsing and formatting happen in your browser. This matters more than usual here — API responses often contain tokens and personal data, and pasting those into a server-side formatter is a real leak.

Why does it say invalid when it looks fine?

Check for a trailing comma, single quotes, or a comment. The error message includes the line and column of the exact character that failed.

Can it handle very large files?

Up to a few megabytes comfortably. Beyond that the browser will slow down, since the whole document is parsed and re-serialised in memory.

Does it sort keys?

No. Key order is preserved exactly as written, because in some formats — package manifests, ordered configs — reordering changes meaning or produces a noisy diff.

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