Advanced Offline POS is a custom Shopify POS extension that keeps your registers selling when the internet does not. When connectivity drops, the app switches to a local-first cart backed by an on-device inventory cache, so staff can scan, ring up, take payment and print receipts without a live connection — then everything auto-resyncs to Shopify the moment you are back online.

This is not an instant App Store download. ECOSIRE builds, installs and supports it for your specific store, theme of operation and hardware. We provision it as a Shopify POS UI Extension (Point of Sale extension) plus a private app authenticated via OAuth with scoped access to the Admin GraphQL API. Product, variant, price and multi-location inventory data are cached locally for fast offline lookup; completed offline sales are held in a durable queue and replayed as orders through the Admin API when the device reconnects.

Because retail outages create real inventory drift, the app reconciles carefully: stock movements are applied against Shopify's multi-location inventory levels with a conflict-safe strategy, and edge cases (oversold variants, duplicated queue entries) are flagged rather than silently overwritten. Order, payment-method and tender metadata are preserved using order metafields so your back office sees a clean, auditable record.

Typical fit: shops in low-connectivity locations, pop-ups, weekend markets and event stalls where a dropped connection currently means a stopped till. We scope your exact tender types, receipt format, printer model and inventory rules during onboarding, then deliver a tested, installed extension. A one-time build fee of $249 covers design, build and installation; ongoing support and Shopify-API compatibility updates are available as an arrangement we agree with you.