The verdict in three sentences
An ERP/CRM integration project for a web app costs between 20,000 and 80,000 EUR in London in 2026, depending on the number of systems and flow complexity. The dominant cost item is not code but data mapping and reconciling master records (customers, products, ledgers). Done well, integration removes up to 60% of double data entry and pays back in 12 to 18 months.
Cost grid by connector type
Cost depends mainly on the target system: a modern REST API is two to three times cheaper to connect than a legacy ERP exposed via SOAP or flat files. Here are the 2026 orders of magnitude seen on the London market.
| System to connect | API type | Connector cost (EUR) | Timeline |
|---|---|---|---|
| Salesforce | REST + webhooks | 5,000 - 12,000 | 3-5 wks |
| HubSpot | native REST | 4,000 - 9,000 | 2-4 wks |
| SAP S/4HANA | OData / BAPI | 12,000 - 20,000 | 6-10 wks |
| Sage / Cegid | files + API | 6,000 - 14,000 | 4-7 wks |
| Microsoft Dynamics | REST + OAuth | 7,000 - 15,000 | 4-8 wks |
| Legacy ERP (SOAP/flat) | SOAP / SFTP | 10,000 - 20,000 | 6-12 wks |
On top of connectors, budget for functional analysis (3,000-8,000 EUR), the orchestration layer and end-to-end testing (5,000-15,000 EUR), and historical data migration.
iPaaS middleware or custom integration?
Two approaches coexist. iPaaS (Make, Workato, Boomi, Mulesoft) speeds setup but adds a recurring monthly subscription. Custom integration costs more to build but removes the subscription and gives full control over critical flows.
| Criterion | iPaaS | Custom |
|---|---|---|
| Upfront cost | 8,000 - 25,000 EUR | 20,000 - 80,000 EUR |
| Monthly subscription | 300 - 2,000 EUR | 0 (hosting only) |
| Setup time | 3-8 wks | 2-5 months |
| Flow control | limited | full |
| High volumes | per-task surcharge | included |
| 3-year TCO (avg) | 45,000 - 95,000 EUR | 30,000 - 90,000 EUR |
Simple rule: under 5 flows and low volumes, iPaaS wins. Beyond that, or with sensitive data, custom becomes cheaper over three years.
Mini case study
Claire, CFO of a 90-person industrial SME in London, runs SAP in-house and Salesforce for sales. Her teams re-key each order twice: roughly 20 hours per week combined, about 4,800 EUR/month of loaded operator time. She commissions a two-way SAP - Salesforce - web app connector for 38,000 EUR, with middleware at 600 EUR/month. Double entry drops 60%: she recovers ~12 hours/week, about 2,880 EUR/month. Payback: around 15 months, excluding reliability and processing-time gains.
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FAQ
What does an ERP/CRM integration really cost in London in 2026?
Expect 20,000 to 80,000 EUR for a full project, or 5,000 to 20,000 EUR per single connector. A simple Salesforce-to-web-app flow can start around 8,000 EUR.
How long does the project take?
From 2 to 5 months depending on the number of systems. A single connector ships in 3 to 6 weeks; a multi-system architecture with reconciliation needs 4 to 5 months.
iPaaS or custom development?
iPaaS is faster and suits low volumes (300-2,000 EUR/month subscription). Custom becomes worthwhile beyond 5 flows or for critical data, with a lower 3-year TCO.
What about maintenance after go-live?
Budget 12 to 20% of the initial cost per year, about 3,000 to 12,000 EUR, to absorb vendor API changes and new fields.
Can you connect an old ERP with no modern API?
Yes, via SOAP, flat files or an intermediary database, but the connector then costs 10,000-20,000 EUR and the timeline rises to 6-12 weeks.
Let's scope your project. Tell us your systems (ERP, CRM, app), the number of flows and target budget, and we'll frame a reliable integration and a 3-year TCO. 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.
