JSON5 Validator

Check whether a JSON5 file (comments, unquoted keys, trailing commas allowed) is valid and see the exact position of any syntax error. Runs in your browser.

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About JSON5 Validator

JSON5 Validator checks whether a JSON5 document is valid and shows the exact reason and position when it is not. JSON5 allows comments, unquoted keys, single quotes, trailing commas, hexadecimal numbers and multi-line strings — but it still has rules, and a single typo can stop a build.

Use it to check config files before committing them, or to confirm that a file a tool rejected really is valid JSON5. Everything runs locally in your browser — the text you paste is never uploaded.

How to use JSON5 Validator

  1. Paste your JSON5 or upload a file.
  2. Press Validate.
  3. Fix the reported problem and validate again.

Key features

  • Full JSON5 syntax support
  • Exact position of the first error
  • Also validates plain JSON and JSONC
  • Uses the reference json5 library

Example

The value for age is missing.

Input
{ name: 'Asha', age: }
Result
JSON5: invalid character '}' at 1:22

When to use JSON5 Validator

  • Checking a JSON5 config file before a build fails because of it.
  • Confirming whether a file is JSON5 (comments allowed) or strict JSON.
  • Finding the exact position of a typo in a long config.

Tips and common problems

  • JSON5 allows comments, trailing commas and unquoted keys — but values must still be complete.
  • If another tool rejects a file that passes here, that tool expects strict JSON.
  • Error positions are shown as line:column.

Frequently asked questions

Yes. JSON5 is a superset of JSON, so any valid JSON passes.