Errors in plain words
Most JSON errors come from habits carried over from JavaScript or Python. Instead of a vague “unexpected token”, this formatter names the problem and points to it:
- Trailing comma after the last item, as in
[1, 2,]. - Single quotes such as
'name'. JSON only allows double quotes. - Keys without quotes, as in
{name: "Ali"}. - Comments with
//or/* */, which JSON does not allow. - Missing commas between values, or a missing colon after a key.
- Bad numbers such as
01,+5or.5. - Raw line breaks or tabs inside a string, which must be written as
nandt.
Lines and columns are counted from 1, the same way code editors count them, so you can jump to the same spot in VS Code or Notepad++.
Large numbers are kept exactly
Many online formatters run your text through the browser’s own JSON reader, which silently changes very large numbers: an ID such as 12345678901234567890 comes back as 12345678901234567000. This tool reads the JSON itself and writes numbers back exactly as you gave them, including trailing zeros such as 1.50.
Format, minify and sort
Formatting adds line breaks and indentation with 2 spaces, 4 spaces or tabs, so nested data is easy to read. Minifying removes every space and line break that JSON does not need, which makes files smaller for APIs and config. Sorting keys puts object keys in A to Z order at every level, which makes two versions of a file easier to compare. Arrays keep their order.
Private and fast
Your JSON never leaves your browser, so it is safe for API responses with tokens or customer data. Files up to 5 MB are accepted; anything over 100 KB is processed in a background worker, so the page stays responsive while it works.