If you want Shopify-level polish but total code-base control, look at a **headless, open-source stack** built around **Medusa JS (Node)** or **Saleor (GraphQL/Django)**. Both ship with PCI-compliant Stripe/PayPal flows, multi-warehouse inventory and plugin markets, yet you own the repos, can deploy on Vercel/AWS, and drop in any React/Next.js, Vue or Svelte front end. For larger catalogs or B2B price lists, **Magento Open Source (a.k.a. Adobe Commerce)** is still the most extensible PHP platform—its modular architecture, Elastic Search, and robust promotion engine beat Shopify’s rigid checkout, albeit with heavier DevOps.

If you prefer a SaaS back-end but want front-end freedom, **BigCommerce + Next.js Commerce** or **Commerce Layer** give you fully documented APIs, no transaction fees, and out-of-the-box multi-storefront features; you host only the presentation layer while they maintain PCI and uptime. Finally, if developer bandwidth is thin and speed matters, **WooCommerce on WP-Engine** is the simplest open-source route—millions of plugins, full database access, and you can still go headless later with WPGraphQL.

Rule of thumb:

* **<\$2 M GMV & small team** → WooCommerce or Medusa (fast start, cheap hosting).
* **High-growth DTC (2–50 M)** → BigCommerce headless or Saleor (scales, API-first).
* **Enterprise/B2B complexity** → Magento OS or Commercetools (rich pricing, ERP hooks).

Whichever path you choose, insist on (1) API coverage for catalog, cart, and promotions, (2) native multi-currency/tax support, and (3) a thriving plugin or marketplace ecosystem—those three factors will save you six figures in custom code as you scale.