Validate JSON in your browser and find the first syntax error by line and column, with a caret under the spot. Duplicate keys and trailing commas fail.
Runs in your browser — your input is processed on this device and never uploaded.
JSON to check. Duplicate object keys are rejected. This page does not run a JSON Schema.
Results appear here.
A JSON validator checks that text is well formed JSON: braces and brackets that match, keys in double quotes, no trailing commas, and strings that escape their special characters. That is a syntax check. It does not tell you whether the document means what you hoped.
Paste JSON and this tool tells you whether it is valid and, if not, where it breaks. It runs in your browser.
A log line that looks like JSON can still be missing a comma on line 40. Feed it to a service and you get a 400 from somewhere else, with nothing pointing at your paste. Here you get the line, the column and a caret.
Trailing commas, single quotes and bare keys are common when people write JSON by hand or copy it out of JavaScript. None of those are JSON. Catching them here is cheaper than catching them in production.
JSON Formatter and Minifier on ToolkitBay uses the same parser and also refuses invalid input, then gives you pretty or compact text when the JSON is valid. Use it when you wanted formatted output rather than a verdict. For YAML, use YAML Formatter and Validator.
JSON Schema validation is a different job: checking types and constraints against a schema document. This page does not do that. jq, Python's json.loads and editor linters cover the same syntax check locally.
The grammar is RFC 8259. Comments are not allowed, and neither are NaN or Infinity. A UTF-8 byte order mark at the start of the text is a frequent copy and paste surprise.
Duplicate keys are legal in the RFC and almost always a defect in practice. Two "id" fields in one object usually means a merge went wrong.
Validation runs in your browser. The JSON is not sent to ToolkitBay's servers.
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