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JSON Formatter

Format, validate, minify, and auto-fix common errors (trailing commas, unquoted keys, comments, smart quotes). Everything runs in your browser.

Valid JSON

Input
Output

How to format JSON

  1. 1
    Paste or uploadDrop JSON into the left pane, or switch to the Upload tab to format one or many files at once (multi-file downloads as a ZIP, entirely in your browser).
  2. 2
    Pick indentChoose 2 spaces, 4 spaces, or Minified. The right pane updates instantly.
  3. 3
    Fix common errors automaticallyIf your JSON has a fixable mistake (trailing commas, single quotes, unquoted keys, Python literals, //comments, smart quotes, doubled outer braces), an Auto-fix banner appears under the error with a one-click preview. Nothing is changed until you click Use fixed version.
  4. 4
    Copy or downloadCopy the formatted JSON to your clipboard or download as a .json file. Batch uploads download as a ZIP with the original filenames.

Frequently asked questions

Is my JSON sent to your server?
No. Formatting, auto-fix, and ZIP creation all run entirely in your browser — nothing is uploaded.
What happens on a syntax error?
We show the exact error from the JSON parser (position, line, column). If the error is one of the common safe-to-fix kinds, you'll also see an Auto-fix banner with a one-click preview in the Output pane.
What can Auto-fix handle?
Trailing commas, single-quoted strings, unquoted object keys, line and block comments, a duplicated outer brace ({{…}}), Python literals (True/False/None), and smart quotes (“ ” ‘ ’). Each proposed fix is previewed in the Output pane before you apply it — nothing is changed silently.
What will Auto-fix NOT do?
Missing commas, missing closing braces or brackets, unterminated strings, and anything where the 'right' fix is ambiguous. For those, we show the error without offering a fix — on purpose. Better to flag the problem than silently corrupt your data.
Is there a file size limit?
No hard limit on pasted input, but very large documents (50+ MB) may slow your browser. Batch upload accepts up to 5 MB per file and 50 files per batch.

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