1Trailing Commas (Comma at end of object/array)
Unlike JavaScript arrays, standard RFC 8259 JSON does not allow trailing commas after the last property or item.
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{ "id": 1, "name": "App", }✓ Fixed
{ "id": 1, "name": "App" }2Single Quotes Instead of Double Quotes
JSON requires double quotes around both property keys and string values. Single quotes triggers Unexpected token '.
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{ 'status': 'success' }✓ Fixed
{ "status": "success" }3Unquoted Property Keys
In JavaScript object literals, key quotes are optional. In standard JSON, unquoted keys produce syntax errors.
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{ title: "Developer Tools" }✓ Fixed
{ "title": "Developer Tools" }4Unescaped Internal Quotes or Backslashes
Quotes inside string values must be escaped with a backslash (\").
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{ "msg": "He said "Hello"" }✓ Fixed
{ "msg": "He said \"Hello\"" }Automatically detect and pinpoint errors in your JSON
Our JSON Validator pinpoints exact line numbers and column positions for any syntax error: