The verdict in three sentences
A custom client portal / extranet in Amsterdam in 2026 costs between 40,000 and 100,000 EUR, delivered in 4 to 7 months. The structuring items are SSO, document management, billing and above all the CRM/ERP integration, which adds about 20% to the budget. ROI is measured in avoided support: a well-designed portal cuts inbound emails and calls by around 40%.
Costed spec by module
| Extranet module | Effort (days) | Cost (EUR) | Priority |
|---|---|---|---|
| Scoping + client journey UX | 12-18 | 7,200 - 10,800 | High |
| SSO / secure authentication | 8-14 | 4,800 - 8,400 | High |
| Document space (upload, versioning) | 12-20 | 7,200 - 12,000 | High |
| Billing / payment history | 10-18 | 6,000 - 10,800 | Medium |
| Messaging / support tickets | 8-15 | 4,800 - 9,000 | Medium |
| CRM/ERP integration | 15-30 | 9,000 - 18,000 | Depends on IS |
| Client dashboards | 8-14 | 4,800 - 8,400 | Medium |
| QA, security, acceptance | 12-18 | 7,200 - 10,800 | High |
Base day rate 600 EUR. Integration with the existing IS (Salesforce, SAP, Sage) is the most variable item: a well-documented API costs 15 days, a legacy ERP without an API can exceed 30 days.
Three portal tiers and their run cost
| Tier | Scope | Timeline | Build (EUR) | Hosting/month |
|---|---|---|---|---|
| Essential | SSO, documents, dashboard | 4-5 months | 40,000 - 60,000 | 100 - 250 EUR |
| Advanced | + billing, tickets, 1 integration | 5-6 months | 60,000 - 85,000 | 250 - 450 EUR |
| Complete | + CRM/ERP, multi-role, SLA | 6-7 months | 85,000 - 100,000+ | 450 - 600 EUR |
Annual maintenance is 15-18% of build. For an advanced portal at 75,000 EUR, budget about 12,000 EUR/year of maintenance and 300 EUR/month hosting, i.e. a run cost of around 15,600 EUR/year.
Mini case study
Sophie, IT director of a 120-person Amsterdam industrial SME, is digitalising the relationship with her 400 B2B clients. She targets an advanced portal: SSO, document space (quotes, invoices, certificates), tickets and an integration with their Sage ERP.
Quote: scoping 15 d, SSO 10 d, documents 16 d, billing 14 d, tickets 12 d, Sage integration 22 d, dashboard 12 d, QA 15 d = 116 days at 600 EUR = 69,600 EUR. Hosting 320 EUR/month, maintenance 12,000 EUR/year.
ROI: customer service handled 900 emails/month at 12 min each, i.e. 180 h/month. A 40% drop frees 72 h/month, about 864 h/year. At a loaded 32 EUR/h, savings reach 27,600 EUR/year. The portal pays back in about 30 months, run included, before counting customer satisfaction.
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
FAQ
Custom portal or off-the-shelf SaaS?
A client-portal SaaS costs 200-800 EUR/month but imposes its limits and puts your data with a third party. Custom costs more upfront but integrates with your IS, carries your brand and avoids per-user subscriptions that explode with growth.
Why is the CRM/ERP integration so expensive?
Because it requires understanding an existing IS, managing two-way sync and securing exchanges. A modern ERP with a REST API costs 15 days; a legacy system without a documented API can require 30 days and bespoke connectors.
Is SSO essential?
For a B2B extranet, yes. It secures access, simplifies users' lives and links to the corporate directory (Azure AD, Google Workspace). Budget 8-14 days depending on the identity provider.
How many support emails can really be avoided?
Around 30-40% by giving the client autonomous access to their documents, invoices and statuses. The gain depends on journey quality: a poorly designed portal merely relocates the frustration.
Can it be delivered in phases?
Yes, and it's recommended. Deliver the core first (SSO + documents) in 4 months, then add billing and integrations. This spreads the budget and lets you adjust to early user feedback.
Let's scope your project. Specify your target modules (SSO, documents, billing, IS integration), your indicative budget and timeline, and we'll deliver a costed spec. 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.
