The verdict in three sentences
When a merchant sells the same stock in store, online and to restaurants, every gap between the website and the ERP turns into a cancelled order, a disappointed customer and hours of re-keying. An off-the-shelf connector at USD 50-300 a month is enough if the ERP is standard and the catalogue simple, while a custom sync at USD 6,000-20,000 becomes necessary once you handle vintages, stock reserved for trade customers, 6 or 12-bottle cases and several warehouses. Either way, the project is justified by the annual cost of errors, often above USD 20,000 for a business of this size.
Where overselling comes from
A 3% rate of orders containing an out-of-stock item is common when online stock is updated by a manual import once a day. The causes repeat from one merchant to the next.
| Cause | Observed frequency (order of magnitude) | Effect |
|---|---|---|
| In-store sale not reflected on the site | 40 to 50% of stockouts | Online order cancelled |
| Restaurant allocation not reserved | 15 to 25% | Conflict between trade and retail customers |
| Vintage change not updated | 10 to 15% | Wrong product shipped or returned |
| Breakage or corked bottle removed from stock | 5 to 10% | Picking blocked |
| Failed CSV import not detected | 5 to 10% | Stock frozen for several days |
| Simultaneous marketplace sales | 5 to 10% | Overselling of rare wines |
Off-the-shelf connector or custom sync
The amounts below are 2026 market estimates in USD (1 USD is about 1.30 SGD). They are not Kolonell prices.
| Criterion | Off-the-shelf connector | Custom sync |
|---|---|---|
| Cost | USD 50 to 300 a month, plus USD 500 to 2,000 setup | USD 6,000 to 20,000, then USD 100 to 300 a month maintenance |
| Timeline | 1 to 3 weeks | 4 to 8 weeks |
| Sync frequency | Usually 15 minutes | Real time via webhooks, or 1 to 5 minutes |
| Vintages and pack sizes | Often handled as simple variants | Dedicated rules per vintage, 6 or 12-bottle case |
| Stock reserved for trade | Rarely | Allocations by channel and customer |
| Multiple warehouses and bonded stock | Depends on ERP | Yes, with picking priority |
| Monitoring and failure alerts | Basic | Logs, email or SMS alerts, automatic retry |
A 15-minute frequency is enough for most items. Real time becomes useful for rare cuvées that sell out in hours, or during private sales and the year-end season, which often accounts for 30 to 40% of online revenue.
The sync must also run the other way: site orders into the ERP, with the data needed for picking and for alcohol compliance, including 9% GST invoicing and records of duty-paid versus bonded stock under Singapore Customs rules.
Mini case study
Wei Ling runs a wine merchant in Singapore handling 9,000 online orders and 2,400 restaurant orders a year. 3% of online orders contain an out-of-stock item, or 270 orders at an average basket of USD 120.
If 60% of those sales are lost, that is USD 19,440 of revenue, or about USD 6,800 of margin at 35%. Each cancellation also costs USD 15 to process, or USD 4,050. Picking errors affect 1.2% of 11,400 orders, or 137 errors at USD 40 each (reshipping, breakage, goodwill), or USD 5,480. Finally, 6 hours of re-keying a week at USD 30 over 47 weeks costs USD 8,460. Total: about USD 24,800 a year.
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A USD 12,000 custom sync that removes 90% of these costs, about USD 22,300, pays back in just over 6 months. A USD 150 a month connector would pay off from the first month, but Wei Ling needs per-restaurant allocations that standard connectors handle poorly.
FAQ
Which ERPs are easiest to connect?
ERPs with a documented REST API connect in 2 to 4 weeks. Older ERPs without an API need scheduled file exchange, which limits frequency to 5 or 15 minutes.
Should we keep a buffer stock on the site?
Yes, a safety threshold of 1 to 3 bottles per item prevents most residual overselling, especially on items also sold in store.
What happens if the sync goes down?
A good sync logs every exchange, retries automatically 3 to 5 times and alerts by email or SMS within 15 minutes.
Can we sync trade prices too?
Yes. Price lists per restaurant can be pushed from the ERP to a trade area on the site, which usually adds USD 2,000 to 5,000 to the project.
How long does a custom project take?
Allow 4 to 8 weeks: 1 week to scope the flows, 2 to 5 weeks of development and 1 to 2 weeks of testing alongside the old process.
Let's scope your project. Tell us your ERP, ecommerce platform and sales channels: we will scope stock and order flows, sync frequency and budget. Detailed quote within 48 h. WhatsApp +221 77 596 93 33, or request your free quote.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
