The verdict in three sentences
A partner extranet connected to your ERP (Sage, SAP) costs in three blocks: the extranet (25,000-50,000 EUR), the API/EDI connector (12,000-30,000 EUR depending on complexity) and the synchronisation middleware (8,000-15,000 EUR). Realistic timeline: 12 to 20 weeks, with a TMA of 12 to 18 % of the build per year. The real hidden costs are not the development, but sync error handling and webhook idempotency.
The 2026 integration cost grid
An ERP extranet is not a website: it is a real-time data exchange system between your ERP and your partners. The budget breaks down like this.
| Block | Scope | Budget 2026 (EUR) | Timeline |
|---|---|---|---|
| Partner extranet | Auth, catalogue, orders, tracking | 25,000 - 50,000 | 8-12 wks |
| ERP connector (API/EDI) | Read stock, write orders | 12,000 - 30,000 | 4-8 wks |
| Sync middleware | Queue, retry, mapping | 8,000 - 15,000 | 3-5 wks |
| Monitoring & alerts | Logs, sync-error dashboard | 4,000 - 9,000 | 2-3 wks |
| Project total | 49,000 - 104,000 | 12-20 wks |
The connector range depends mostly on the quality of your ERP's API: a modern REST API costs far less than an EDI integration or direct database access.
The technical watch-points
Half the budget of an ERP extranet goes into the reliability of the exchanges, not the screens. Here are the risks to cost at scoping.
| Watch-point | Risk if neglected | Mitigation cost |
|---|---|---|
| Webhook idempotency | Duplicated orders in ERP | 3,000 - 6,000 EUR |
| Sync error handling | Wrong stock, phantom stockouts | 4,000 - 8,000 EUR |
| ERP SLA / availability | Extranet blocked if ERP down | Cache + queue |
| Data mapping | Inconsistent product codes | 2,000 - 5,000 EUR |
| Volume / performance | Slow sync at peaks | Batch + pagination |
A non-idempotent webhook that replays an order can cost thousands in disputes. It is the first item to secure.
Mini case study
Sarah, IT director of a B2B distribution SME in Amsterdam, wanted to give her 40 resellers an extranet to order and see stock in real time, connected to Sage. Before, orders arrived by email and were re-keyed into the ERP: ~9 h/week of entry and a 6 % error rate.
Costed project: extranet 38,000 EUR + Sage connector 22,000 EUR + middleware 11,000 EUR = 71,000 EUR, delivered in 17 weeks. Result: re-keying disappears (~9 h/week saved, ~11,700 EUR/year), the error rate falls below 1 %, and resellers order 24/7. With a 15 % TMA (10,650 EUR/year), the project pays back in about 3 years, before the commercial gain from round-the-clock availability.
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FAQ
Why is the connector so expensive?
Because price depends on the target ERP: a modern REST API connects fast, but an old Sage or an SAP with EDI needs bespoke development, mapping and thorough testing. Hence the 12,000-30,000 EUR range.
What happens if the ERP goes down?
A well-built extranet uses a queue and a cache: orders are stored and replayed once the ERP is back, with no loss. That is exactly the middleware's job.
Can you sync in real time or in batch?
Both combine: real time via webhooks for orders, nightly batch for large volumes (catalogue, pricing). The choice depends on volume and business needs.
How much is annual maintenance?
Expect 12 to 18 % of the build per year, i.e. ~8,500 to 18,700 EUR for a 70,000 EUR project. ERP integrations need more TMA than plain websites because the ERP itself evolves.
Do you need the ERP vendor's approval?
Not always, but you must check API access terms and any connector licence costs. We audit this at scoping to avoid nasty surprises.
Let's scope your project. Tell us your ERP (Sage, SAP, other), your partner count and the flows to sync, and we will cost the integration block by block. 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.
