ZXing - Barcode Scanner for Android
Lynkee Reader - Lynkee Reader is the best QR & Barcode Reader application on the market.
MKH Barcode Reader - This tool can be used to scan QR codes on your PC or tablet. Note: a webcam is required.
QuickMark - QuickMark makes everything possible.
QR Code Reader “Q” - Formerly QR Code Reader “Q,” now QRQR, is a smart code reader application.
Obsqr - obsqr is an open-source, fast and lightweight QR scanner for Android.