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JSON Validator

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Check whether a JSON document is valid. Errors are reported with line and column, plus a plain-English explanation of the likely cause.

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How to use this tool

  1. Paste the JSON to check.
  2. Click Validate.
  3. If invalid, jump to the reported line and column and fix the highlighted cause.
  4. Re-validate until the green summary appears.

About this tool

"Unexpected token" errors in production often trace back to hand-edited JSON. This validator uses the strict native parser and translates its errors into actionable messages — pointing at the line and column and naming the usual suspects: trailing commas, single quotes instead of double, unquoted keys, comments (JSON has none), and unescaped control characters in strings. Valid documents get a summary of their structure (type, key count, nesting depth).

Frequently asked questions

Why is JSON with comments invalid?
The JSON specification has no comment syntax. Some tools accept them anyway (JSONC), but strict parsers — including the ones in browsers and most languages — reject them.
Are single quotes really not allowed?
Correct. JSON strings and keys must use double quotes. Single quotes are a JavaScript habit that strict JSON parsers reject.
The validator says valid but my API rejects the JSON — why?
The syntax is valid, but the API likely expects a particular schema: specific keys, types or value ranges. Check the API's documentation for its required structure.

Related tools

JSON FormatterPaste minified or messy JSON and get a cleanly indented, readable version. Invalid JSON produces an error with the line and position of the problem.JSON MinifierStrip every unnecessary space and line break from JSON to get the smallest valid representation — with the size saving shown.CSV to JSONTurn CSV data — pasted or from a file — into a JSON array of objects, using the header row as keys. Quoted fields and embedded commas are handled correctly.