The verdict in three sentences
An ERP-to-web-app integration is priced per data flow, not as a flat fee: expect 12,000 to 40,000 EUR depending on whether you sync 2 flows (products, stock) or 6 (customers, orders, invoices, deliveries). The right 2026 pattern is webhooks plus a message queue for resilience, not raw polling that saturates the ERP API. The realistic timeline is 4 to 10 weeks: direct integration for 2-3 flows, middleware as soon as you exceed 4 flows or have several consumers.
What each integration flow costs
An integration project breaks down by data flow. Each flow has its own field mapping, reconciliation logic and tests. Here are 2026 ballpark figures for a New York mid-market buyer.
| Synchronized flow | Direction | Complexity | Indicative 2026 cost (EUR) |
|---|---|---|---|
| Product catalog | ERP to Web | Low | 2,500 - 4,000 |
| Stock levels | ERP to Web | Medium | 3,000 - 5,500 |
| Customer / account records | Bidirectional | Medium | 4,000 - 7,000 |
| Orders | Web to ERP | High | 5,000 - 9,000 |
| Invoices / credit notes | ERP to Web | High | 4,500 - 8,000 |
| Deliveries / tracking | ERP to Web | Medium | 3,000 - 6,000 |
A technical foundation (authentication, logs, monitoring, error handling) adds 3,000 to 6,000 EUR regardless of the number of flows. This is the investment that keeps the whole thing maintainable.
Webhooks vs polling vs middleware
The architecture choice drives reliability and run cost. In 2026, avoid polling every 30 seconds, which drains your API quotas and delays the data.
| Criterion | Direct polling | Webhooks + queue | iPaaS middleware |
|---|---|---|---|
| Build cost | Lowest | Medium | Medium to high |
| Data latency | 1 to 30 min | Near real-time | Near real-time |
| Failure resilience | Low | High (replay) | High |
| Load on ERP API | High | Low | Low |
| Monthly run cost | Low | Low | 150 - 800 EUR |
| Recommended threshold | 1 simple flow | 2 to 5 flows | 5+ flows, multi-consumer |
The message queue (RabbitMQ, AWS SQS, or a Postgres queue table) is the detail that changes everything: if the ERP is unavailable, the message is retained and replayed instead of lost. That is what separates a toy integration from a production one.
Mini case study
Mark, IT director of an industrial-parts distribution SMB in New York, runs a Sage X3 and a web ordering app for his 140 trade customers. His sales reps re-keyed web orders into Sage: about 25 hours a week at 32 EUR fully loaded, i.e. 33,000 EUR a year, plus a 3% entry error rate. He commissions 3 flows (products, stock, orders) with webhooks and a message queue for 19,500 EUR, delivered in 6 weeks. The payback is reached in 7 months, and the order error rate drops below 0.4%.
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FAQ
Do I need middleware or a direct integration?
Below 3-4 flows and a single consumer, direct integration is enough and costs less. Beyond that, or if several applications read the same data, middleware avoids an explosion of point-to-point connections.
How long does the project take?
Expect 4 to 6 weeks for 2-3 flows, 8 to 10 weeks for 5-6 flows with middleware. The field-mapping and reconciliation-testing phase often accounts for 40% of the timeline.
What happens if the ERP goes down?
With a message queue, events are retained and replayed automatically once the ERP is back. Without a queue, you lose the data emitted during the outage: that is the main risk of a low-end integration.
What annual maintenance cost should I plan for?
Budget 12 to 18% of the build cost per year for maintenance, plus the cost of any iPaaS (150 to 800 EUR per month depending on operation volume).
Can we start small and expand?
Yes, and it is recommended: ship the most profitable flow first (often orders or stock), validate reliability, then add the following flows on the same technical foundation.
Let's scope your project. Tell us your ERP (SAP, Sage, Dynamics), the flows to sync and your monthly order volume, and we will frame a scope between 12,000 and 40,000 EUR. 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.
