How We Integrated SAP with Shopify Plus

SAP integrations are the most technically demanding projects we undertake. When a large UK homewares retailer came to us with 40,000 SKUs, a SAP S/4HANA ERP, and a Shopify Plus store that was manually synced via weekly CSV exports, the operational pain was immense. Stock errors, overselling, and reporting delays were costing them an estimated £80,000 a year in operational waste.

The Integration Requirements

• Real-time stock level sync from SAP to Shopify (target: under 5 minutes lag).
• Bi-directional order sync — Shopify orders flowing to SAP for fulfilment, SAP fulfilment status updating Shopify.
• Customer master data sync for B2B accounts.
• Product data managed in SAP and pushed to Shopify — including pricing, descriptions, and images.
• Financial reconciliation feed for the client's finance team.

Architecture Decisions

We chose a middleware architecture rather than direct API-to-API integration. SAP's API layer has rate limiting considerations and complex authentication, and a direct connection creates tight coupling that makes future changes expensive. We used a managed integration platform (Celigo) as the middleware, configured with custom transformation logic for the client's specific SAP configuration.

Handling Stock in Real Time

SAP stock updates trigger a webhook to our middleware, which transforms the data and calls Shopify's Inventory API. For 40,000 SKUs with multiple warehouse locations, this generates significant event volume. We batched updates intelligently — aggregating changes within a 60-second window before pushing to Shopify — achieving sub-3-minute lag in practice with 99.8% API success rate.

Order Flow

Every Shopify order triggers an immediate push to SAP, where it enters the standard fulfilment workflow. SAP creates a delivery note and, on despatch, sends a fulfilment confirmation back via middleware to Shopify. Customers receive their shipping confirmation email within minutes of SAP confirming despatch — not on the following morning when a batch process previously ran.

Results

• Stock accuracy improved from 78% to 99.1%.
• Oversell incidents dropped from 120 per month to under 5.
• Order processing time from purchase to SAP reduced from next-day to under 3 minutes.
• Finance team saved 12 hours per week previously spent on manual reconciliation.
• Estimated annual operational saving of £95,000.