bcWebCam - Scan barcodes and QR Codes with your computer web cam
AliPrice - AliExpress Price Tracker app lets you track the price history of any item from many online retailers like AliExpress, Daraz, and Amazon, etc.
ZXing - Barcode Scanner for Android
idealo - Idealo is a free to use mobile application that helps you to find products, compare price and make an informed decision.
Barcode to PC: Wi-Fi scanner - Turn your smartphone into a real barcode scanner
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.