Does formatting change the data?

No. It only changes whitespace, unless you turn on Sort keys.

No. Parsing and formatting happen in your browser. It is not put in the URL.

Why was valid-looking JSON rejected?

JSON needs double quotes around keys and strings, and it doesn't allow trailing commas or comments.

JSON Formatter

Pretty-print, minify, and validate JSON in your browser. Nothing is uploaded.

Runs entirely in your browser. Nothing is uploaded.

JSON6 lines · 86 characters

IndentSort keys

Ctrl/⌘ + Enter

object · 4 keys · 98 bytes

Result

9 lines · 98 characters

{
  "name": "Nice Tools",
  "live": true,
  "tools": [
    "JSON",
    "Regex"
  ],
  "count": 2
}

Worked example

Paste {"name":"Nice Tools","tools":["JSON","Regex"]}. Format indents it. Minify puts it on one line. An extra comma is reported with a line and column so you can jump to it.

FAQ

Does formatting change the data?: No. It only changes whitespace, unless you turn on Sort keys.
Is my JSON uploaded?: No. Parsing and formatting happen in your browser. It is not put in the URL.
Why was valid-looking JSON rejected?: JSON needs double quotes around keys and strings, and it doesn't allow trailing commas or comments.