JSON Formatter

{
  "name": "AEON Toolhub",
  "tools": 25,
  "free": true,
  "categories": [
    "productivity",
    "text",
    "developer"
  ],
  "owner": {
    "handle": "oiurireis"
  }
}

What does this JSON formatter do?

Paste messy or minified JSON and it comes back indented, colour-highlighted, and validated. This free JSON formatter from ÆON Toolhub runs entirely in your browser, so an API response with a token in it never leaves your machine. Pick two spaces, four spaces, tabs, or minify to a single line, sort the keys alphabetically, then copy the result or download it as a .json file.

If the JSON is broken, it does not just say "invalid": it tells you the line and column and shows the offending line with a caret under the exact character.

How do you use it?

Paste your JSON into the input box. Formatting happens as you type, with no button to press.

Pick the indentation. Two spaces is the common default, four spaces suits some codebases, tabs matches editors configured that way, and Minify strips everything to one line.

Sort the keys if you need to. Useful before diffing two files.

Fix any error. The message shows exactly where parsing stopped.

Copy or download. Take the result to your editor, or save it as a file.

How do you find the error in broken JSON?

Browsers report a character offset, something like position 412. That is almost useless in a 400-line file, which is why this tool converts it into a line and column, prints that line, and marks the exact character with a caret.

The usual culprits, in order of how often they show up:

• A trailing comma after the last item in an object or array.
• Single quotes instead of double quotes.
• Unquoted keys, which JavaScript allows but JSON does not.
• Comments, which strict JSON has no concept of.
• A missing or extra bracket, usually after a copy and paste.

JavaScript object syntax is more relaxed than JSON, so text lifted straight out of code often needs these small corrections first.

What do the statistics tell you?

Under the output you get the final size, the number of keys, and the nesting depth of the structure. Depth is the one people underestimate: deeply nested payloads are harder to consume, and a depth above five or six is usually a sign the shape could be flattened. When you switch to Minify, the tool also shows the percentage saved, which is typically 15% to 30% for a file that was indented.

Is formatting the same as changing the data?

No. Formatting only changes whitespace: indentation and line breaks. The keys, values, types, and array order are untouched, so the parsed result is identical before and after. Sorting keys is the one option that rewrites structure, and even then only the order of object keys changes, never the values, and never the order of arrays, which is meaningful data.

Your JSON stays private

The formatter runs entirely in your browser with the same JSON engine your code uses. What you paste is never uploaded, logged, or stored, and it clears when you close the tab. That makes it safe for API responses, config files, and anything containing keys or tokens, and it keeps working offline once the page has loaded.