The verdict in three sentences
Connecting your online store, ERP and stock in real time costs either 300 to 1,500 EUR/month with an iPaaS connector (Alumio-type cloud integration) or 12,000 to 35,000 EUR for custom middleware. The right choice depends on the number of flows and the sync frequency: beyond three systems and minute-level syncs, custom pays off. The real gain is measured in oversells avoided (70 to 95 %) and 3 to 6 days/month of re-keying removed.
iPaaS or custom middleware
iPaaS is subscription-based and quick to configure; custom middleware is paid once and finely handles your business rules (multi-warehouse, stock reservations, per-customer pricing).
| Criterion | iPaaS (Alumio & sim.) | Custom middleware |
|---|---|---|
| Entry cost | 3,000 - 8,000 EUR (setup) | 12,000 - 35,000 EUR |
| Recurring cost | 300 - 1,500 EUR/mo | 400 - 900 EUR/mo (maint.) |
| Rollout time | 3 - 6 weeks | 8 - 14 weeks |
| Complex business rules | Limited | Fully custom |
| Multi-warehouse | Plan-dependent | Native |
| EU hosting / GDPR | Vendor-dependent | Controlled |
| Ownership | No | Yes |
Sync frequency and oversell impact
The tighter the sync, the less you sell a product already out of stock. Moving from nightly to minute-level sync dramatically cuts oversells.
| Sync frequency | Max stock lag | Oversells avoided | Re-keying effort |
|---|---|---|---|
| Nightly batch (1x/day) | 24 h | baseline | 3 - 6 d/mo |
| Every 15 min | 15 min | 70 - 80 % | 1 - 2 d/mo |
| Every 5 min | 5 min | 85 - 90 % | < 1 d/mo |
| Real time (1 min) | 1 min | 90 - 95 % | near zero |
ROI of avoided stock errors
An oversell is expensive: refund, handling cost, lost customer. Here is the 2026 order of magnitude for a Singapore SME at 400 orders/month.
| Line item | Without integration | With real-time integration |
|---|---|---|
| Oversells/month | 30 (7.5 %) | 2 (0.5 %) |
| Average cost per oversell | 45 EUR | 45 EUR |
| Monthly oversell loss | 1,350 EUR | 90 EUR |
| Re-keying (days) | 4 d at 250 EUR/d | 0.3 d |
| Re-keying cost/month | 1,000 EUR | 75 EUR |
| Monthly total | 2,350 EUR | 165 EUR |
Mini case study
Thomas, logistics director of a professional-equipment SME in Singapore, chooses custom middleware at 22,000 EUR plus 600 EUR/month maintenance. Before, he lost 2,350 EUR/month to oversells and re-keying. After real-time integration, that line falls to 165 EUR/month, saving 2,185 EUR every month. The upfront investment is repaid in about 11 months, and the team reclaims nearly 4 person-days monthly, reassigned to customer service.
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FAQ
iPaaS or custom: how to decide?
If you link two standard systems with simple rules, iPaaS at 300-1,500 EUR/month is enough. From three systems, multi-warehouse or per-customer pricing, custom middleware becomes more cost-effective over three years.
What sync frequency should I target?
Every 5 minutes covers the vast majority of needs and avoids 85 to 90 % of oversells. Strict real time (1 min) is justified for very tight SKUs or flash sales.
How long to deploy?
Allow 3 to 6 weeks on iPaaS and 8 to 14 weeks for custom middleware, including load testing and cutover.
Does data stay in Europe?
Yes if you require it: EU hosting and GDPR compliance are contractual, native on middleware you control, and to be verified with the iPaaS vendor.
What maintenance budget?
Between 400 and 900 EUR/month for custom middleware, covering fixes, new flows and evolving stock rules.
Let's scope your project. Tell us your systems (store, ERP, WMS), order volume and target sync frequency, and we will price the right iPaaS or custom integration. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
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.