Web POS & invoicing system -- 2

We are looking to build a Web POS system with the following min set of features.

Minimum List Of features required
o Enhance Dashboard
o Categories
o Sub-categories
o Products
Variants
Modifiers
Options
Transfers
Adjustment
o Raw Material
Managing Raw materials
o Promos
o Billing Module
Invoicing
Quotations
Sales Orders
Purchasing
o Payment
We will provide the hooks using our payment switch, or the code
o APIs
A comprehensive set of APIs



• Invoicing Note
We need to be able to create invoices and send the invoices (it is simply a sale like) via links so they can be paid online (based on the current merchant active gateway)
We will need reminders for overdue invoices
The APIs should also accept the request from mobile and auto-create the invoice based on the request


More information will be provided to the selected contractor.
if you have built a POS system before, you will know what we are looking for.

The system must be built using .NET core, MSSQL.
The system is part of a multi-application system, so you need to follow strict guidelines.