Most require programming skills (and then you are the one that need to make it secure) or use a CMS plugin (WordPress) and then you are back where Shopify fish for customers.
I use to run our businesses webshop with my own code but having less time to keep up on it I gave up and switched to OSS CMS instead. Not Shopify though as they take (at least back when I checked) a huge chunk of money for the service. I can't remember the amount but it was something like 3%? For a medium business that's enough to hire developers to create your own! Now I use a payment provider (bank) instead and it costs nothing except the payment processor fee I already had to pay.
