The verdict in three sentences
An API connector between your custom app and an ERP or CRM costs, in 2026, between 5,000 and 18,000 EUR depending on complexity, plus middleware/iPaaS at 200-600 EUR/month. The real risk line item is not the initial build but API versioning and maintenance at 10-15 %/year. The question is never "sync or not" but real-time or batch — that single choice drives 60 % of the budget.
What each connector costs in 2026
A CIO in Nice who wants to link a custom business app to Sage/Cegid and HubSpot/Salesforce should budget per system, not as one lump sum. Each brick has its own authentication logic, call quotas and rate of API breakage.
| System to connect | Connector cost (EUR) | Timeline | Recommended mode |
|---|---|---|---|
| ERP Sage 100 / X3 | 8,000 - 18,000 | 4 - 8 wks | Nightly batch |
| ERP Cegid | 7,000 - 15,000 | 4 - 7 wks | Batch + webhooks |
| CRM HubSpot | 5,000 - 9,000 | 3 - 5 wks | Real-time (REST) |
| CRM Salesforce | 6,000 - 12,000 | 3 - 6 wks | Real-time |
| Billing (Pennylane, Sellsy) | 4,000 - 8,000 | 2 - 4 wks | Webhooks |
| Payroll / HRIS | 5,000 - 10,000 | 3 - 6 wks | Monthly batch |
An iPaaS (make, Workato, self-hosted n8n) pools authentication and monitoring: budget 200-600 EUR/month depending on operation volume, often cheaper than maintaining 4 hand-coded connectors.
Real-time or batch: the trade-off that drives the budget
Real-time sync (webhooks, an API call per event) is convenient but fragile: every ERP version bump can break the flow. Nightly batch is robust and 30-40 % cheaper to maintain, but introduces a delay.
| Criterion | Real-time | Batch |
|---|---|---|
| Data latency | < 5 seconds | 2 - 24 hours |
| Maintenance/year | 15 % of build | 10 % of build |
| Sensitivity to API versioning | High | Moderate |
| Typical use case | E-commerce stock, live quotes | Accounting, reporting, payroll |
| Silent breakage risk | High | Low (alerts) |
Simple rule: real-time only where stale data costs money (stock, availability, price). Everything else in batch.
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Mini case study
Marc, CIO of a distribution SME in Nice (55 staff), commissions an order-management app. He connects Sage X3 (nightly batch, 12,000 EUR) and HubSpot (real-time, 7,000 EUR), plus an iPaaS at 350 EUR/month. Initial investment: 19,000 EUR + 4,200 EUR/year subscription and 2,850 EUR/year maintenance (15 %). By eliminating dual order/CRM entry he saves 18 h/week of re-keying at 32 EUR/h loaded, i.e. ~27,000 EUR/year. Payback in under 12 months.
FAQ
Why not connect everything in real-time? Because every real-time flow increases the failure surface. Across 4 connectors, moving 2 to batch cuts annual maintenance by roughly 30 % with no real business impact.
Who pays when the vendor changes its API? That is the "API maintenance" line (10-15 %/year of the build). A major Salesforce or Sage API update can require 2-5 dev days, i.e. a one-off 1,200-3,000 EUR.
iPaaS or custom code? Below 3 simple connectors, custom code is enough. Beyond that, an iPaaS (200-600 EUR/month) lowers total cost and centralizes logs and alerts.
How long for a first connector? Budget 3-8 weeks per system, in parallel. A 4-connector project usually ships in 8-12 weeks with a dedicated team.
Can we start small? Yes: start with the highest-ROI connector (often CRM or billing), validate, then add the rest in waves.
Let's scope your project. Tell us which ERP/CRM to connect, flow volume and desired mode (real-time or batch): we price each connector separately. 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.
