Spartacus

SAP's open-source Angular storefront for SAP Commerce Cloud

Best for: Enterprise teams already running SAP Commerce Cloud who need an Angular-based, SEO-friendly composable storefront on top of it.
Skip if: You're not on SAP Commerce Cloud - Spartacus is tightly coupled to that backend and isn't a general-purpose e-commerce starter.

Spartacus (now officially called SAP Commerce Cloud composable storefront) is a lean, open-source Angular-based storefront that talks to SAP Commerce Cloud exclusively through its REST API. It runs decoupled from the backend on its own server, supports PWA capabilities, server-side rendering for SEO, and CMS-driven page composition, and is developed and maintained by the SAP Commerce Cloud team.

Pros

Free, open source, and maintained directly by SAP's Commerce Cloud team
Decoupled architecture with SSR and PWA support suits SEO-sensitive enterprise storefronts
Upgradable library structure keeps custom storefronts compatible with new SAP releases

Cons

Only useful if you're already running SAP Commerce Cloud as the backend
spartacus.dev, the domain often associated with the project, is not SAP's official site and currently redirects elsewhere - use github.com/SAP/spartacus instead
Angular-specific and enterprise-oriented, not aimed at indie/solo developers