Shift4Shop

Shift4Shop (formerly 3dcart) is a fully-featured, US-focused SaaS platform known for packing a vast array of built-in tools. Its standout offer is a completely free plan for US merchants processing payments through Shift4. It includes robust SEO features, email marketing, blogging, and advanced product options without needing numerous apps. The platform caters well to small and mid-sized businesses looking for an all-in-one solution with strong B2B capabilities.

The interface can feel dated compared to competitors, and its ecosystem is smaller, but its value proposition is powerful for cost-conscious merchants who need extensive native functionality.