Custom secure client portal development cost in London (2026)

The verdict in three sentences

A custom secure client portal in London costs between EUR 25,000 and 70,000 for a first production-ready MVP, depending on the number of connectors and the authentication level. The real gain is not the portal itself but the drop in support load (-35% on average) and the professional image it projects to your B2B clients. Expect 3 to 5 months from design to launch, with a developer day rate between EUR 450 and 650 on the London market.

What the 2026 budget covers

A client portal is not just a website: it is an authenticated space exposing data from your systems (invoicing, CRM, ticketing). The budget depends mainly on the number of connectors and the required security level.

Prices are 2026 order-of-magnitude estimates for a serious London studio or agency, excluding the annual maintenance (TMA) to budget separately.

Custom build vs off-the-shelf SaaS

Generic SaaS client portals exist. The choice depends on your customisation needs and data sensitivity.

Custom becomes rational when you have specific connectors, a strong branding need, or data-residency constraints (local hosting, strict GDPR).

Mini case study

Claire, IT Director of a B2B services SME in London (180 staff, 400 active clients), receives about 600 support requests/month, 40% of them asking "where is my invoice / document". A custom portal at EUR 48,000 (MVP + accounting connector) pays back as follows: 240 requests avoided/month x 12 min x EUR 35/loaded hour = ~EUR 1,680/month saved, or ~EUR 20,000/year. With maintenance at EUR 7,200/year, ROI is reached in under 4 years, before counting client satisfaction and fewer payment chasers.

FAQ

How much does a custom client portal cost in London in 2026?

Between EUR 25,000 and 70,000 for a production MVP. The number-one factor is the count of connectors (invoicing, CRM, ERP); each real-time integration adds EUR 5,000 to 12,000.

How long does delivery take?

Expect 3 to 5 months. An MVP without SSO or heavy connectors can ship in 10-12 weeks; a portal with Azure AD SSO and two ERP connectors takes 4 to 6 months.

Is SSO mandatory?

Not for an MVP: email + MFA is often enough at first. SSO (SAML/OIDC) becomes essential once enterprise clients require it, and represents roughly EUR 4,000 to 8,000 of development.

What annual maintenance budget should I plan?

A realistic maintenance figure is 15 to 20% of the build cost, i.e. EUR 4,000 to 12,000/year, covering security, updates and small improvements.

Can we start small then expand?

Yes, and it is recommended: ship a documents + invoicing MVP, measure the support drop, then add tickets, e-signature and connectors in budgeted batches.

Let's scope your project. Tell us your target connectors (invoicing, CRM), the number of users and your SSO requirement, and we will quote the MVP then a roadmap. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.