Are there modules for the famous (php) cms or frameworks for inventory management? (like pizza or sushi bar)?

Question

CMS

There are many paid options, we settled on one, but there is an idea to write again or use the ready-made ones on your servers.

Answer 1

In OpenCart, you can specify the quantity "in stock" for all products. Also, when ordering from the site, OpenCart can automatically subtract the ordered product from "availability". There is also on-line processing of orders with statuses.