Is my JSON sent to a server?

No. Parsing and formatting run entirely in your browser. Nothing you paste leaves your device.

Why is a trailing comma an error?

The JSON specification doesn't allow a comma after the last item in an object or array. JavaScript and many config formats do, which is why it's such a common mistake when copying data between them.

What's the difference between formatting and minifying?

Formatting adds line breaks and indentation so people can read it. Minifying removes all optional whitespace to make the file as small as possible. Both represent exactly the same data.

Free developer tool

JSON Formatter and Validator

Validate JSON with exact line and column errors, then pretty-print or minify it. Big numbers are kept exactly as written.

Sort keys A–Z

JSON input

Formatted

Validate and format JSON in one step

Paste JSON and it's checked as you type. If something's wrong, you get the exact line and column, a plain-English reason (a trailing comma, a single-quoted string, a missing comma between properties) and a pointer to the spot. If it's valid, it's formatted with your choice of indentation, or minified to a single line.

The validator follows the JSON standard (RFC 8259) strictly, so it flags things JavaScript accepts but JSON doesn't, like comments, NaN and unquoted keys. Numbers are copied as written, so IDs like 12345678901234567890 aren't rounded the way JSON.parse would round them.

Handy for SEO work

Check JSON-LD structured data before pasting it into a page.
Read API responses from Search Console or analytics exports.
Sort keys A–Z to compare two configs side by side.
Find duplicate keys, which most parsers silently overwrite.

Frequently asked questions

Is my JSON sent to a server?: No. Parsing and formatting run entirely in your browser. Nothing you paste leaves your device.
Why is a trailing comma an error?: The JSON specification doesn't allow a comma after the last item in an object or array. JavaScript and many config formats do, which is why it's such a common mistake when copying data between them.
What's the difference between formatting and minifying?: Formatting adds line breaks and indentation so people can read it. Minifying removes all optional whitespace to make the file as small as possible. Both represent exactly the same data.