I recently built an open-source inventory and POS system called CAAD ERP , originally designed to solve a specific problem at my university: when managing inventory, sales, and tab debts, my student lounge had to rely on over-engineered POS systems or overly simple Excel sheets. To solve this, I built a simple yet complete system tailored specifically for these operations. The differentiator is that instead of setting up a traditional database, the system uses an Excel workbook as the sourc...