Dual-Mode E-Commerce Builder

I need a robust e-commerce website builder that merchants can use both offline and online without changing workflows. The focus is on physical products, so the core engine must include real-time inventory tracking and an accurate shipping-rate calculator that remains functional even when the user is temporarily offline, then syncs automatically once a connection is restored.

Store owners should be able to design their sites three ways—intuitive drag-and-drop blocks, a gallery of modern responsive templates, or raw HTML/CSS for full control. Switching among these modes has to be seamless so a merchant can start with a template, refine it visually, and finish with code tweaks in a single session.

Key deliverables
• A cross-platform builder that runs locally (desktop app, PWA, or comparable approach) and mirrors all functionality in a cloud dashboard
• Product catalog module limited to physical goods, with inventory adjustment, low-stock alerts, and bulk import/export
• Shipping calculator that supports multiple carriers and custom rules, available offline and updated on sync
• Visual editor + template library + code editor working side-by-side
• One-click publishing and version rollback

Acceptance is based on a fully installable package, browser-based counterpart, clean source code, and a short video walkthrough demonstrating offline creation, online sync, and live deployment.