“Ecommerce SEO” is not one category. Each platform has its own structural strengths, bottlenecks, and scaling ceilings. Retainers that apply a template across all of them underperform. Every engagement scope is calibrated against the stack your store actually runs.
Shopify and Shopify Plus
Shopify is the default mid-market ecommerce platform and the one we handle most. The strengths are speed (Hydra/edge rendering on Shopify Plus), built-in product schema, and strong conversion-optimised templates. The bottlenecks are faceted-navigation handling (particularly around collection URL canonicalisation), product variant canonical discipline, and third-party app JavaScript bloat. Shopify retainers typically run £1,800–£4,500/month UK, $2,500–$7,500/month US for single-store work; £3,500–£9,000/month UK, $4,500–$12,000/month US for multi-store Plus engagements with international expansion.
WooCommerce and WordPress
WooCommerce is the right choice when content and commerce need to coexist (publishers, content-led brands, subscription-box businesses). The strengths are content-layer flexibility, WordPress editorial tooling, and deep theme-level control. The bottlenecks are performance (Core Web Vitals tuning is harder than on Shopify), plugin bloat, and hosting constraints that bite at scale. Retainers £1,500–£4,000/month UK, $2,000–$6,000/month US.
BigCommerce
BigCommerce suits mid-market and wholesale-enabled retailers and handles B2B flows better than Shopify. The strengths are headless-ready architecture, strong API surface, and robust product variant handling. SEO work typically focuses on category-hub architecture, pro-forma pricing visibility for B2B, and migration-discipline for clients moving off legacy stacks. Retainers £2,000–£5,000/month UK, $2,500–$7,500/month US.
Custom Next.js Commerce and Hydrogen
Custom stacks (Next.js Commerce, Shopify Hydrogen, Saleor, Medusa) win on performance and flexibility at the cost of shipped-ecommerce out-of-the-box. Retainers sit at the upper end because engineering collaboration is required for every significant SEO change. Typical ranges £3,500–£8,500/month UK, $4,500–$11,000/month US.
Amazon and marketplace SEO
Amazon SEO (A9 algorithm, product listing optimisation, backend keyword work) is a separate discipline from Google SEO. For brands running both Shopify/Custom DTC + Amazon, we scope the two engagements separately because the measurement, lexicon, and tactics don't meaningfully overlap. Marketplace-only engagements £1,500–£4,500/month UK, $2,000–$6,500/month US.