The barcode used with the Visitor or Service Provider badge utilises Code-128 1D Barcodes.
Code 128 is a very high-density barcode symbology. It is used for alphanumeric or numeric-only barcodes. It can encode all 128 characters of ASCII and, by use of an extension character (FNC4), the Latin-1 characters defined in ISO/IEC 8859-1
Code 128 is widely used and can be decoded with virtually any barcode reader. WhosOnLocation recommends either the Motorola/Zebra DS9208 or the Socket CHS 7Qi scanner. Find out more here.