BigCommerce vs Shopify is the decision that shapes how a growing UK or Irish retailer sells online for years, not months. Both platforms are established, well-supported, and used by thousands of businesses, but they solve different problems: one prioritises fast, polished setup, the other prioritises native technical depth as a catalogue grows. This guide sets out the current state of both platforms for 2026, including the fee changes that have altered the cost picture and the catalogue limits that have shifted since last year. If you’ve read a comparison written for a US audience and struggled to find anything on VAT, the Windsor Framework, or UK carriers, this one fills that gap. The right choice depends on your catalogue, your team’s technical capability, and where your business is headed over the next few years.