How to validate JSON online for free
Quick answer
Paste the JSON in - if it is invalid, the exact line and column of the problem is shown, so you do not have to scan the whole document by eye. Valid JSON is also pretty-printed for readability.
- 1Paste the JSON.
- 2If it is invalid, the specific line and column of the error is shown.
- 3Fix it and re-check, or copy the pretty-printed valid version.
Free, no sign-up, and your file is read on your own device rather than uploaded.
A single misplaced comma, an unescaped quote, or a trailing comma in the wrong place is enough to make an entire JSON document invalid - and the resulting parser error from most programming languages does not always point clearly at the actual problem.
A dedicated validator parses the document the same way any JSON parser would, and reports precisely where it stopped being able to make sense of it, which is usually much faster than manually re-reading a large payload.
Step by step
Read the result
Valid JSON is pretty-printed; invalid JSON shows exactly where parsing failed.
JSON Formatter
Tips
- A trailing comma after the last item in an array or object is one of the most common reasons JSON that "looks right" turns out to be invalid - JSON, unlike JavaScript object literals, does not allow one.
- Property names and string values must use double quotes, not single quotes - a document copied from JavaScript code often fails validation for exactly this reason.
Common problems
The JSON looks correct but still fails to validate.
Check for a trailing comma, single quotes instead of double quotes, or an unescaped quote inside a string value - all three are easy to miss by eye and are the most common causes.
Frequently asked questions
- Is my JSON uploaded to a server to validate it?
- No - validation runs using your browser's own JSON engine, entirely client-side.
- Does this also format the JSON, not just validate it?
- Yes - valid JSON is pretty-printed with proper indentation, which doubles as a readable, formatted copy you can use directly.
Related related tools
- JSON FormatterBeautify, minify and validate JSON, with real error messages.
- Base64 Encoder / DecoderEncode text to Base64 or decode it back, including Unicode and emoji.
Ready to do it?
Free, no sign-up, and nothing is uploaded to a server.