Ecwid

Ecwid (by Lightspeed) is a 'commerce widget' designed to add a store to any existing website, social page, or marketplace. It works by embedding a shopping cart via a snippet of code, syncing inventory and orders across all channels. This makes it perfect for bloggers, small businesses with an established site (on WordPress, Wix, etc.), or those selling heavily on Facebook/Instagram.

It offers a free plan and simple setup. While not a full website builder, its strength is omnichannel simplicity. It's less suited for building a large, standalone brand storefront but excels as a lightweight, unified sales layer across a fragmented online presence.