The verdict in three sentences
A well-designed API integration eliminates double entry between your website, CRM and billing tool, saving your teams 10 to 20 hours per month. In 2026 in London, a realistic budget runs from 12,000 EUR for two simple connectors to 40,000 EUR for a full flow with historical migration and real-time webhooks. The real risk is not the upfront cost but API maintenance: plan for 15 to 20 % of the project value per year.
What each integration building block costs
Price depends on the number of systems to connect, the required data freshness and the quality of the source APIs. Here are the 2026 orders of magnitude on the London market.
| Building block | 2026 cost (EUR) | Timeline |
|---|---|---|
| Website to CRM connector (leads) | 3,000 - 6,000 | 1-2 wk |
| CRM to billing connector | 4,000 - 8,000 | 2-3 wk |
| Catalogue/product sync | 3,500 - 7,000 | 1-2 wk |
| Real-time webhooks + retry queue | 4,000 - 9,000 | 2-3 wk |
| Historical data migration | 2,500 - 8,000 | 1-3 wk |
| Monitoring dashboard | 3,000 - 6,000 | 1-2 wk |
A typical SME project combines 3 to 4 of these blocks, hence the overall 12,000 to 40,000 EUR range.
iPaaS or custom development
The central question is whether an iPaaS (Make, Zapier, n8n) is enough or whether you need dedicated code. iPaaS speeds up the start but its monthly cost climbs with operation volume.
| Criterion | iPaaS (Make/Zapier) | Custom |
|---|---|---|
| Setup cost | 1,500 - 5,000 EUR | 12,000 - 40,000 EUR |
| Monthly cost | 30 - 400 EUR/mo | 0 (excl. hosting) |
| Supported volume | Medium (per-task billing) | High |
| Complex business logic | Limited | Full |
| Vendor lock-in | Strong | Low |
| Best for | < 50,000 ops/month | Critical flows, high volumes |
Simple rule: under 50,000 monthly operations with standard rules, iPaaS is unbeatable. Beyond that, or when business logic gets specific, custom becomes cheaper over 24 months.
Mini case study
Sarah, finance director of a 45-person industrial SME in London, had every order re-keyed three times: website, CRM, billing software. Two people spent about 15 hours per month on it, with a 4 % error rate. We delivered three connectors and webhooks for 19,500 EUR in 8 weeks. At a loaded cost of 35 EUR/hour, the 15 hours saved are worth 6,300 EUR per year, not counting avoided billing errors. Payback on time alone lands in just over three years, much faster once reliability is factored in.
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FAQ
How long does an API integration take?
Between 6 and 12 weeks for an SME scope of 3 to 4 connectors. A single simple connector can ship in 2 to 3 weeks.
Do I have to pay annual maintenance?
Yes. Third-party APIs evolve, version and deprecate. Plan for 15 to 20 % of the project cost per year to monitor, fix and adapt the flows.
What happens if an API goes down?
A serious integration includes a retry queue and alerts. Failed operations are replayed automatically and you are notified, preventing any silent data loss.
Can we start small then scale?
Yes, and it is recommended. Start with the connector that removes the most expensive pain (often CRM to billing), measure the gain, then add the next flows.
Is iPaaS enough for an SME?
In 60 % of cases yes, as long as volumes stay moderate and logic standard. You switch to custom when monthly iPaaS costs exceed the amortised cost of a dedicated build.
Let's scope your project. Tell us which systems to connect (website, CRM, billing, ERP), your monthly order volume and an indicative budget, and we will propose the most cost-efficient architecture. 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.
