The verdict in three sentences
A custom client portal for a London services SME costs between EUR 25,000 and 60,000 in 2026 depending on the modules, with delivery in 3 to 5 months. An MVP at EUR 15,000-25,000 validates adoption in 8-10 weeks before you invest further. The payback shows quickly: 25-40% fewer support calls and 10-20% shorter payment delays.
What a client portal costs in 2026
The price depends mainly on the number of modules and how deeply it integrates with your existing tools (ERP, billing, CRM). Here are 2026 orders of magnitude.
| Scope | Modules included | Cost | Timeline |
|---|---|---|---|
| MVP | Auth, order tracking, documents | EUR 15,000-25,000 | 8-10 wks |
| Standard | + notifications, invoices, search | EUR 25,000-40,000 | 3-4 months |
| Advanced | + SSO, e-signature, API | EUR 40,000-60,000 | 4-5 months |
| Complex custom | + business workflows, multi-entity | EUR 60,000+ | 5-7 months |
Maintenance (TMA) runs 8-15% of project cost per year, i.e. EUR 3,000-9,000/year for a standard portal.
What moves the bill
A few line items weigh heavily and should be scoped early to avoid surprises.
| Item | Budget impact | Note |
|---|---|---|
| SSO / single sign-on | +EUR 3,000-8,000 | Azure AD, Google, OAuth |
| E-signature | +EUR 4,000-10,000 | Yousign, DocuSign, eIDAS |
| ERP/billing integration | +20-30% of project | Sage, Xero, QuickBooks |
| Email/SMS notifications | +EUR 2,000-5,000 | Reminders, alerts |
| Mobile app (PWA) | +EUR 6,000-15,000 | Optional |
Advice: start with the MVP covering the single function your clients need most (tracking their orders), then add modules in iterations funded by the gains.
Mini case study
Julien, operations director of a technical services SME in London (45 staff), receives 180 calls/month from clients asking about order status and invoice copies. At 6 minutes per call and a loaded cost of EUR 28/h, that is 18 h/month, roughly EUR 504/month of admin time.
He invests EUR 22,000 in a portal MVP (order tracking + invoice access), delivered in 9 weeks. Calls drop 35%, i.e. 63 avoided calls/month (6.3 h saved, ~EUR 176/month). More importantly, putting invoices online cuts the average payment delay by 14%, freeing up cash. Payback on support and cash gains alone: about 14-16 months, before any advanced modules.
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FAQ
Custom portal or off-the-shelf SaaS?
A client SaaS (Zendesk, Clustdoc type) costs EUR 20-80/user/month and fits standard needs. Custom is justified once you have specific workflows or deep ERP integration, generally beyond 50-100 active clients.
How long to deliver an MVP?
Allow 8 to 10 weeks for an MVP with one or two core functions, using a small team (1 lead + 1-2 developers). A tight scope is the key to hitting that timeline.
What maintenance budget should I plan?
Between 8 and 15% of project cost per year, i.e. EUR 3,000-9,000/year for a standard portal, covering security, minor evolutions and technical support.
Can the portal connect to my billing software?
Yes, via API or connectors. Integrating Sage, Xero or QuickBooks represents 20-30% of the project budget depending on the API richness.
Is e-signature legally compliant?
Yes, with an eIDAS provider (Yousign, DocuSign). Budget EUR 4,000-10,000 for integration plus a signer subscription (from ~EUR 30/month).
Let's scope your project. Tell us your priority modules (tracking, invoices, SSO, signature), your indicative budget and the number of clients to equip. 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.
