Shopify

Shopify treats a store as the whole product rather than a feature bolted to a website. Inventory, payments, shipping rates, tax, discounts and the point-of-sale in a physical shop are one system, and the parts of selling that quietly break other platforms — a tax rule, a shipping band, an out-of-stock variant — are handled rather than approximated.

The app market is the mechanism that keeps it fitting. Where the core does not cover a trade's particular way of selling, something in the market usually does, and the platform stays supported underneath it. Support runs around the clock, and the volume of published material means an unusual problem has usually been written up already.

The cost is that it is priced as a business system and behaves like one. The advertised trial rate is a promotional figure that rises steeply once it ends, using a payment processor other than the platform's own attracts a percentage on every order, and the in-person tools are a further monthly charge per location. For a business whose sales justify that it is money well spent, and for one testing whether it has a business at all it is a heavy place to start.