Its customized version of Point of sale software its have both online and offline database (you need to add your API to use the online database)

Feature
-> User Authentication
-> Stock List
-> Sell product
-> Sell report
-> Invoice System
-> Bluetooth Printer (To print invoice)
-> Due List
-> Online Data Synchronise System

More details and screenshot about this project https://www.behance.net/gallery/54364123/AndroPos

#Open Source APP
GitHub link: https://github.com/ashraf789/Android-POS

Username: admin
User password: 123456

Note: it's just a demo app