The verdict in three sentences
For an Amsterdam wholesaler, an API integration between the ERP and the B2B portal costs EUR 12,000 to 30,000 excl. VAT, depending on the number of data flows and the complexity of customer pricing. The most profitable piece is stock and order synchronisation, which removes about 80% of manual data entry from the second month. Plan for 8 to 14 weeks and middleware at around EUR 200 a month to make the exchanges reliable.
What you actually pay for: the flows to connect
An ERP integration is not priced per website but per data flow. Each flow has its own business rules, error cases and tests. Here are 2026 ballpark figures for a mid-sized wholesaler in the Amsterdam region.
| Flow | Direction | Frequency | Indicative cost excl. VAT |
|---|---|---|---|
| Item catalogue and product sheets | ERP to site | Once a day | EUR 2,000 to 4,000 |
| Available stock per warehouse | ERP to site | Every 15 minutes | EUR 2,500 to 5,000 |
| Customer prices and discounts | ERP to site | On every change | EUR 3,000 to 7,000 |
| Web orders | Site to ERP | Real time | EUR 2,500 to 6,000 |
| Order status and parcel tracking | ERP to site | Every 30 minutes | EUR 1,000 to 3,000 |
| PDF invoices and credit balance | ERP to site | Once a day | EUR 1,000 to 3,000 |
| Customer accounts and contacts | Both ways | Hourly | EUR 1,500 to 2,500 |
A minimal scope (catalogue, stock, orders) lands around EUR 12,000. A full scope with negotiated prices, credit balances and invoices reaches EUR 25,000 to 30,000. Customer pricing is the most underestimated flow: price lists per product family, cascading discounts, net delivered prices. It usually takes two workshops with finance to map it all.
Middleware, direct connector or file export?
Three architectures coexist in 2026. The choice affects the upfront cost, but mostly the maintenance over the next three years.
| Criterion | Scheduled CSV export | Direct API connector | Middleware (iPaaS) |
|---|---|---|---|
| Setup cost excl. VAT | EUR 5,000 to 9,000 | EUR 10,000 to 22,000 | EUR 12,000 to 30,000 |
| Monthly cost | Almost nil | EUR 50 to 100 hosting | EUR 150 to 300 |
| Stock freshness | 1 to 4 times a day | Real time | 5 to 15 minutes |
| Error recovery | Manual | Must be built | Native, with log |
| Adding a 2nd channel | Hard | Medium | Easy |
| Fit for 1,200 orders a month | Borderline | Yes | Yes |
At 1,200 orders a month, CSV exports quickly hit their limits: stock-outs shown late, duplicate orders, re-keying. Middleware costs a little more upfront, but it logs every message, replays failures automatically and makes it easy to add a marketplace or a sales rep app later. With Sage X3, it relies on the SOAP or REST web services available in your version; Exact and AFAS, common in the Netherlands, expose REST APIs.
Typical project timeline
| Phase | Duration | Deliverable |
|---|---|---|
| Scoping and flow mapping | 2 weeks | Flow matrix, pricing rules |
| ERP test environment and access | 1 week | Test plan, technical accounts |
| Priority flows development | 3 to 5 weeks | Stock, orders, catalogue |
| Customer pricing and credit | 2 to 3 weeks | Net prices per account |
| Pilot with 10 customers | 1 to 2 weeks | Sign-off, fixes |
| Go-live and hypercare | 1 week | Monitoring, alerts |
Total lead time is 8 to 14 weeks. The critical path is rarely the code: it is access to an ERP test environment and the availability of your ERP partner. Book those slots as soon as the contract is signed.
Mini case study
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Daan, IT director of an industrial supplies wholesaler in Amsterdam, handles 1,200 orders a month, 70% of which still arrive by email. Two order desk assistants spend an average of 6 minutes per order re-keying into the ERP, i.e. 120 hours a month.
After integration through middleware (EUR 24,000 project cost and EUR 200 a month), manual entry drops by 80%: 24 hours of exception handling remain. The 96 hours freed up, valued at EUR 35 fully loaded, are worth EUR 3,360 a month. After the middleware fee, the net gain is EUR 3,160 a month: the project pays for itself in under 8 months, before counting fewer pricing errors and customer disputes.
FAQ
Do we need to upgrade our ERP to connect a B2B site?
Not necessarily. Recent versions expose REST APIs, older ones SOAP web services that middleware can use. A 2 to 3-day technical audit, around EUR 2,000 excl. VAT, settles the question.
Why sync stock every 15 minutes rather than in real time?
A 15-minute interval covers more than 95% of a wholesaler's needs and spares the ERP load. Real time is mostly justified for fast-moving items, which can be handled separately.
Who maintains the integration after go-live?
Budget a maintenance contract of EUR 300 to 800 excl. VAT a month covering monitoring, version upgrades and fixes. The middleware raises an alert automatically when a flow fails.
Can each customer see different prices?
Yes, it is the core of a B2B portal. The pricing flow often accounts for 20 to 25% of the total budget, because ERP discounts must be reproduced exactly.
What are the security risks?
Exchanges run over HTTPS with limited-rights technical accounts. No direct access to the ERP database is opened from the internet, which remains the baseline rule.
Let's scope your project. Send us your list of flows, your ERP version and your order volume: we will price a scope between EUR 12,000 and 30,000 with an 8 to 14-week plan. 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.
