We use Opencart for nearly all of our e-commerce websites. We are comfortable changing the default functions to deliver a totally bespoke experience.
Custom route to checkout
A lot of the customisation work we do is with digital to print websites so that people can create something online and have it printed by a professional printer. We build Your Staff ID to allow them to sell their custom staff id cards on Opencart, which really highlights the flexibility of the platform.
We are happy coding something really custom, or making a more standard e-commerce website. Ratpak sell products online and most of them don't require customisation - view the Ratpak website here.