Is it safe to paste API responses with real data?

Yes. Parsing and formatting happen locally via your browser’s built-in JSON engine. Nothing is transmitted or logged.

Why does my JSON fail with "Unexpected token"?

Common causes: trailing commas, single quotes instead of double quotes, unquoted keys, or comments — none of which are valid JSON.

What is the difference between formatting and minifying?

Formatting adds indentation and line breaks for humans; minifying removes all insignificant whitespace to make the payload as small as possible.

How large a file can it handle?

The native JSON parser comfortably handles files of tens of megabytes; very large files are limited only by your device’s memory.

JSON Formatter & Validator

Format, validate and minify JSON instantly in your browser. Clear error messages with line hints — your data is never uploaded.

JSON input

Indent

Output

How to use the JSON Formatter & Validator

Paste your JSON into the input box.
Choose an indentation width (2 or 4 spaces).
Click Format to pretty-print, or Minify to strip all whitespace.
If the JSON is invalid, the exact parser error is shown so you can fix it.
Click Copy to grab the result.

About this tool

Minified JSON from an API response is nearly unreadable, and a single misplaced comma can break a config file. This formatter pretty-prints valid JSON with your preferred indentation and pinpoints the first syntax error when it is not valid.

Because the tool uses the browser’s native JSON engine — the same one JavaScript itself uses — its verdict on validity is authoritative, and it is fast enough to format multi-megabyte payloads instantly.

Privacy matters with JSON more than most formats, since payloads often contain tokens, emails or customer records. Here, nothing leaves your machine: no upload, no server, no logs. You can even load the page, disconnect from the internet, and keep formatting.

Frequently asked questions

Is it safe to paste API responses with real data?: Yes. Parsing and formatting happen locally via your browser’s built-in JSON engine. Nothing is transmitted or logged.
Why does my JSON fail with "Unexpected token"?: Common causes: trailing commas, single quotes instead of double quotes, unquoted keys, or comments — none of which are valid JSON.
What is the difference between formatting and minifying?: Formatting adds indentation and line breaks for humans; minifying removes all insignificant whitespace to make the payload as small as possible.
How large a file can it handle?: The native JSON parser comfortably handles files of tens of megabytes; very large files are limited only by your device’s memory.

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