JSON Formatter & Validator
Paste JSON to beautify, validate or minify it. Invalid JSON is pinpointed to the exact line and column. Everything runs in your browser — nothing is uploaded. Last reviewed 2026-06-19.
How to use the JSON formatter
- Paste your JSON into the input box.
- Click Format / Beautify to pretty-print it (choose 2-space, 4-space or tab indent), Minify to strip whitespace, or Validate to just check it.
- If the JSON is invalid, the message shows the exact line and column of the problem.
- Copy or Download the result.
Format vs. validate vs. minify
Validating checks whether your text is well-formed JSON. Formatting (beautifying) re-indents valid JSON so a human can read nested structures. Minifying removes every non-essential space and newline so the payload is as small as possible — useful before sending JSON over the network or embedding it. None of these change your data: keys, values, types and key order stay exactly as written; only whitespace differs.
Common reasons JSON is invalid
- Trailing comma —
{"a":1,}is invalid; JSON allows no comma after the last item. - Single quotes — strings and keys must use
"double quotes", never'. - Unquoted keys —
{name:"x"}must be{"name":"x"}. - Comments — JSON has no
//or/* */comments. - Wrong literals — booleans and the null value must be lowercase (
true,false,null); JavaScript-only keywords are not valid JSON. - Mismatched brackets — every
{and[needs its closing partner.
Is it private?
Yes. The tool uses your browser's native JSON.parse and JSON.stringify —
nothing is sent to a server, so it is safe to paste internal API responses, tokens or config. It also
works offline once the page has loaded.
Frequently asked questions
- Is my JSON uploaded to a server?
- No. Formatting, validating and minifying all run in your browser with JavaScript. Your data never leaves your device, which makes the tool fast and safe for sensitive payloads.
- Why is my JSON invalid?
- The most common causes are a trailing comma after the last item, single quotes instead of double quotes, unquoted object keys, comments (JSON has none), or a missing bracket/brace. This tool points you to the exact line and column where parsing failed.
- What is the difference between formatting, validating and minifying?
- Validating checks whether the text is well-formed JSON. Formatting (beautifying) re-indents valid JSON so it is readable. Minifying strips all whitespace to make it as small as possible for transport. This tool does all three from one box.
- Does formatting change my data?
- No. Beautifying and minifying only change whitespace — the keys, values, types and structure are identical. Object key order is preserved as written.
- How large a file can it handle?
- Because it runs in your browser, it comfortably handles typical API responses and config files (multiple MB). Extremely large files are limited only by your device memory, not an upload limit.