Case Study
How a Custom Shopify-ERP Integration Eliminated Stock Discrepancies for a UK Retailer
A real-time bidirectional sync between Shopify and a legacy warehouse ERP — eliminating 12 monthly oversells, lifting inventory accuracy to 99.8% and cutting order processing from 4 hours to 40 minutes.
0
Oversells per month (was 12)
99.8%
Inventory accuracy
40 min
Order processing (was 4 hrs)
The challenge
12 oversells per month — and peak season was 8 weeks away
The client was running a Shopify store alongside a legacy ERP system in their warehouse. Because the two systems weren't connected, stock levels were updated manually every morning by a member of the warehouse team.
Between updates, Shopify was selling stock that had already been committed to wholesale orders in the ERP — averaging 12 oversell incidents per month. Each oversell required manual cancellation, customer communication and a refund, costing roughly £85 in admin time and lost goodwill per incident.
How it works
Inside the build
01
Map every stock movement
Audited each path stock could move along — wholesale orders, returns, transfers — so no edge case was missed by the integration.
02
Build real-time inventory push
Used Shopify's GraphQL Admin API to push updates from the ERP into Shopify within 60 seconds of any stock movement.
03
Build webhook-based order push
Shopify orders push back to the ERP instantly on placement via a custom webhook, so warehouse staff see new orders in their picking system immediately.
04
Audit log + failure alerts
All sync events logged to Supabase. Any failed sync triggers an immediate email alert so issues are caught before they become customer-facing.
Benefits
What the business actually gains
0 oversells
Down from 12 incidents per month — eliminating a recurring source of refunds and bad reviews.
99.8% accuracy
Inventory accuracy improved from approximately 94% to 99.8% across both systems.
45 min/day saved
Daily manual stock update task eliminated entirely — every morning, every warehouse.
4 hrs → 40 min
Order processing time reduced as orders now appear in the ERP picking system instantly.
Zero stock complaints
Peak season traded without a single stock-related customer complaint.
ROI in month 1
Return on investment achieved within the first month of operation.
Features
Everything the platform delivers
- Real-time bidirectional Shopify ⇄ ERP sync (≤60s latency)
- GraphQL Admin API for high-volume inventory queries
- Custom webhook pipeline for instant order push
- Per-event Supabase audit log with status indicators
- Email failure alerts with full error context
- Peak-season ready: stress tested for 10× normal volume
Technology
Built on a modern stack
Why it matters
This is what bespoke automation looks like
Two takeaways from this build.
1. GraphQL beat REST for this workload. Inventory queries needed to be granular and high-volume; the GraphQL Admin API let us request exactly the fields we needed and stay well inside Shopify's rate limits.
2. The audit log earned its keep on day one. Within hours of going live, the log surfaced an edge case in the ERP's wholesale order flow we'd never have spotted in testing. Fixed in 30 minutes — no customers affected.
"We went into Black Friday genuinely calm for the first time in years. Stock was right, orders flowed, no awkward refund emails. The system just works."
— E-commerce Manager, UK Homeware Retailer (anonymised)
Services used
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FAQ
Frequently asked questions
Will this work with my ERP?
Almost certainly. If your ERP exposes any kind of API or database access, we can build a sync. We've integrated with NetSuite, Xero, Sage, custom in-house ERPs and several niche warehouse systems.
How fast is 'real-time'?
Stock movements propagate within 60 seconds. Orders appear in the ERP within seconds of placement on Shopify.
What if a sync fails?
Every event is logged. Any failure triggers an email alert with the full error context, and the system retries automatically with exponential backoff.
How long does this take to build?
Typically four to six weeks for a single-channel sync. Multi-warehouse or multi-channel setups can take eight to twelve weeks.
Ready to automate your business?
This is just one example of what's possible. If you have a repetitive process costing you time, we can build a custom tool to handle it.
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