JSON validator online: fast checks before shipping

A JSON validator should do 3 things well: reject invalid syntax, show exactly where it fails, and give you formatted output you can read.

Common validation failures

• Single quotes instead of double quotes for keys or strings.
• Trailing commas after the last array/object item.
• Unescaped line breaks or quote characters inside strings.
• Pasting HTML error pages and trying to parse them as JSON.

// Invalid JSON
{
  "name": "Kim",
  "active": true,
}

// Valid JSON
{
  "name": "Kim",
  "active": true
}