The verdict in three sentences
An ERP to B2B portal API integration costs between 12,000 and 40,000 EUR (excl. VAT) for a Berlin distributor in 2026, depending on the ERP and the number of flows to synchronise. The most expensive item is not the code but the data mapping: item numbers, customer-specific price lists, sales units and warehouses. Properly scoped, the project ships in 6 to 12 weeks and ends the double entry that currently shows out-of-stock items as available and wrong prices on the portal.
What a connector costs depending on your ERP
Price depends first on how open the ERP is. Odoo exposes a full XML-RPC and REST API, SAP Business One offers the Service Layer, Microsoft Dynamics 365 Business Central has OData APIs, while Sage 100 and older DATEV-linked setups often require middleware or scheduled exports. Here are 2026 ballpark figures for a distributor B2B portal (2,000 to 20,000 SKUs) in Germany, where developer day rates run 750 to 1,100 EUR.
| ERP | Access method | Connector cost (EUR) | Timeline | Watch-outs |
|---|---|---|---|---|
| Odoo 17/18 | Native REST / XML-RPC | 12,000 - 20,000 | 6 - 8 weeks | Custom modules to map |
| SAP Business One | Service Layer (OData) | 20,000 - 40,000 | 8 - 12 weeks | Access licences, special prices |
| Dynamics 365 Business Central | OData / REST APIs | 15,000 - 30,000 | 6 - 10 weeks | Extension (AL) work for custom fields |
| Sage 100 (DE) | Middleware or SDK | 16,000 - 32,000 | 8 - 10 weeks | On-premise server to expose |
| proALPHA / abas | Web services | 22,000 - 40,000 | 10 - 12 weeks | Vendor involvement often required |
| In-house ERP | SQL database or flat files | 14,000 - 32,000 | 8 - 12 weeks | No API contract, regression risk |
On top of this, budget maintenance at 10 to 15% of the initial cost per year (1,200 to 6,000 EUR) and, for SAP, possible technical user licences.
Real time or every 15 minutes: which flow for which need
Not every flow needs real time. Available stock and order validation benefit from instant sync, while catalogue and prices can run every 15 minutes or overnight. This choice directly drives budget and load on the ERP.
| Flow | Direction | Recommended frequency | Indicative extra cost (EUR) | Expected gain |
|---|---|---|---|---|
| Stock per warehouse | ERP to portal | Real time (webhook) or 5 min | 2,500 - 6,000 | No more out-of-stock sales |
| Customer prices and discounts | ERP to portal | Every 15 min | 3,000 - 7,500 | Correct price per account |
| Item catalogue | ERP to portal | Nightly + on demand | 2,000 - 5,000 | Up-to-date listings, no re-entry |
| Orders | Portal to ERP | Real time | 4,000 - 9,000 | -90% entry errors |
| Statuses and invoices | ERP to portal | Every 15 min | 2,000 - 4,500 | Fewer customer service calls |
| Credit limits | ERP to portal | Hourly | 1,500 - 4,000 | Automatic block of risky accounts |
A robust architecture relies on a message queue (RabbitMQ, Redis or a cloud queue), automatic retries when the ERP is down and an exchange log your team can read. Without these safeguards, a cheap connector can lose orders on a Friday evening without anyone noticing. In Germany, also check GoBD requirements: order and invoice data passed between systems must remain traceable and unaltered.
What makes a quote slip
Three issues explain most overruns: inconsistent item numbers between ERP and portal, price lists with undocumented exceptions, and no test environment on the ERP side. Ask for a 2 to 4 day scoping workshop (2,000 to 4,500 EUR) that delivers a data dictionary, a flow matrix and an acceptance test plan. That document also lets you compare several quotes on the same basis.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Lukas, IT director of an industrial supplies distributor in Berlin (45 employees, 8,000 SKUs, SAP Business One), has two assistants re-entering about 140 portal orders a day into the ERP. Time spent: 3.5 hours a day, about 770 hours a year at 38 EUR fully loaded, so 29,300 EUR a year. Add around 2% faulty orders at an average rework cost of 55 EUR, another 7,700 EUR. The chosen connector costs 31,000 EUR plus 4,000 EUR of yearly maintenance. With 90% less re-entry and fewer errors, annual savings exceed 33,300 EUR: payback in roughly 13 months.
FAQ
Do I need to replace my ERP to connect a B2B portal?
Rarely. Sage, Dynamics or an in-house ERP can be connected through middleware for 14,000 to 32,000 EUR. Replacing an ERP often costs 100,000 EUR or more and only makes sense if the system is end of life.
Is an off-the-shelf connector enough?
Ready-made connectors (300 to 1,500 EUR a month) cover standard cases. As soon as you have customer-specific pricing, several warehouses or packaging units, a custom build at 12,000 to 40,000 EUR is usually more reliable.
What happens if the ERP goes down?
With a message queue, portal orders are held and replayed automatically. Budget 2,000 to 4,000 EUR for this mechanism and an email or Slack alert on repeated failures.
How long before the first flow is live?
Working in batches, the stock flow can go live by week 4 or 5. The full project ends between 6 and 12 weeks depending on the ERP.
Who owns the connector code?
Require an IP transfer and Git repository access in the contract. That is the condition to switch provider without starting over.
Let's scope your project. Send us your ERP, volumes and the flows to automate: we will price a custom connector in the 12,000 to 40,000 EUR range with a 6 to 12 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.
