Is there a cms/plugin to implement a store with the ability to add lots by the user?

Question

Online shopping

Are there any cms or plugins to extend the usual online store engine, to the possibility of adding a product, by the user himself?
That is:
1. Authorization through social. network
2. Filling the store with your goods

Answer 1

1) It is available in almost any popular CMS (if not, it is installed with plugins and modules)
2) Here it is a little more difficult to have something similar for OpenCart. But I think you need to properly configure the rights of user groups and simply give the ability to add products to a specific category.