DevConvertor
JSON Tools

JSON Validator

Validate JSON syntax and get an exact line and column for the first error, without needing to reformat the input to find the problem.

Paste JSON to check it’s well-formed

Related tools

JSON Formatter

Pretty-print and validate JSON with configurable indentation.

JSON Beautifier

Reformat JSON with your choice of indentation.

JSON Viewer

Browse JSON as a collapsible, searchable tree.

Features

  • Instant valid/invalid status as you type
  • Exact line and column for the first syntax error
  • No false positives — uses the same JSON grammar your code will parse with
  • Copy the input once it's confirmed valid

How to use

  1. Paste the JSON you want to check.
  2. The status banner updates immediately.
  3. If invalid, the message tells you what's wrong and exactly where.

Example

Common error this catches — a trailing comma:

{ "a": 1, "b": 2, }

Reported as invalid, with the line and column of the offending comma.

FAQ

What counts as valid JSON here?
Anything JSON.parse in your browser accepts under the standard JSON grammar — this tool doesn't apply any extra, stricter rules beyond what JSON actually requires, so there are no false positives from an overly picky validator.
Why does it flag trailing commas as errors?
Trailing commas after the last item in an object or array are not valid JSON, even though they're allowed in JavaScript object literals. This is one of the most common reasons JSON copied from code fails to validate.
Can I fix the JSON here too?
This tool is validation-only. Once your JSON is valid, use the JSON Formatter to pretty-print it or the JSON Minifier to compress it.