Django SaaS Billing & Inventory

I’m putting together a cross-platform billing and inventory SaaS that must run smoothly on the web (React) and mobile (Flutter). The core stack is already chosen: a Django backend with a PostgreSQL database, all deployed on AWS... (Budget: ₹12500 - ₹37500 INR, Jobs: API Development, Django, Flutter, Payment Gateway Integration, Payment Processing, PHP, PostgreSQL, Python, SaaS, Software Architecture)