JSON validator with readable error messages

Valid JSON follows a short list of strict rules. When a document breaks one, JSONWeave tells you which rule, where, and what the fix looks like, instead of a single "Unexpected token".

Validate JSON in the workspace

What validation checks

JSONWeave checks that the document is strictly valid JSON. It does not check a JSON Schema, so it validates syntax, not whether the data has the shape your application expects.

Problems it reports

Trailing commas after the last item
Unquoted property names
Single-quoted strings
Unterminated strings
Missing commas, colons or values
Unclosed objects and arrays
Unexpected tokens and trailing content after the document
Duplicate keys inside one object
Comments, which JSON does not allow

Example

The unquoted key, the single-quoted string and the trailing commas below are each listed in the diagnostics panel and marked in the editor.

Invalid: four problems

{
  name: 'api-gateway',
  "ports": [80, 443,],
}

From validation to a fix

Run Validate JSON for a summary. If the document is not valid, open the repair preview to see a corrected version and apply it with one click.

Frequently asked questions

How do I fix invalid JSON?

Read the error list to find each problem, or open the repair preview in JSONWeave to see a corrected document and apply it.

Does it validate against a JSON Schema?

No. JSONWeave checks JSON syntax only.

Ready to try it on your own JSON?

Open the workspace, paste or drop a file, and nothing leaves your browser.