OpenCart is a free and open source shopping cart platform built on PHP.

MultiMerch is an extension for OpenCart that implements a vendor/seller system and allows vendors to list and sell their products in the marketplace (eBay, Amazon, Aliexpress).

MultiMerch comes as a download that is designed to be installed on top of a new or existing OpenCart store and supports unlimited vendors and products.

MultiMerch uses a free vQmod modification system (link to vqmod vs ocmod) to make changes in OpenCart files via xml mods and does not overwrite or require manual modifications to any OpenCart files directly.