The verdict in three sentences
A custom connector between your CRM and billing tool costs between 5,000 and 20,000 EUR in 2026, delivered in 3 to 8 weeks. It kills double data entry, saves your teams 5 to 15 hours a week and cuts billing errors by around 80%. The structuring choice: a custom connector (full control, fixed cost) or an iPaaS like Make/Zapier (fast but recurring cost that climbs with volume).
Custom connector or iPaaS
Between Sellsy, Pennylane, HubSpot, Axonaut and your tools, two paths exist. iPaaS starts fast but bills per task; custom costs more upfront and nothing after.
| Criterion | iPaaS (Make/Zapier) | Custom connector |
|---|---|---|
| Setup cost | 500-3,000 EUR | 5,000-20,000 EUR |
| Recurring cost | 20-300 EUR/month by volume | negligible run |
| Bidirectional sync | limited | full |
| Complex business logic | hard | ✅ |
| Real-time webhooks | partial | ✅ |
| Profitability at high volume | degrades | ✅ |
| Delivery time | 1-2 weeks | 3-8 weeks |
What the connector automates and its ROI
The connector syncs customers, quotes, orders and invoices via API and webhooks, both ways: a quote signed in the CRM generates the invoice, and a received payment updates the status.
| Automated flow | Before (manual) | After connector | 2026 gain |
|---|---|---|---|
| CRM customer → billing | re-keying | instant | -100% entry |
| Signed quote → invoice | 10-15 min | automatic | ~-95% |
| Payment status → CRM | manual check | real time | continuous |
| Billing errors | frequent | rare | ~-80% |
| Admin time/week | 5-15 h | < 1 h | 5-15 h saved |
Mini case study
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Élodie, finance director at a 22-person services agency in Bordeaux, loses 12 hours a week copying quotes and invoices between HubSpot and Pennylane, with costly errors. She invests 11,000 EUR in a custom bidirectional connector, delivered in 5 weeks. Result: admin time drops to 1 h/week, i.e. 11 hours saved. At a loaded 40 EUR/h, savings reach ~1,900 EUR/month: the connector pays back in under 6 months, on top of fewer billing disputes.
FAQ
What is the real cost of a connector? Between 5,000 and 20,000 EUR depending on the number of flows, business-logic complexity and both tools' API quality. Well-documented APIs (Pennylane, HubSpot, Sellsy) lower the bill.
iPaaS or custom: how to decide? iPaaS suits simple flows and low volumes. Once logic gets complex or volume climbs, custom becomes cheaper over 12-24 months.
What is the delivery time? Plan for 3 to 8 weeks depending on the number of flows and testing. A single-flow connector sometimes ships in 2 weeks.
Is the sync real time? Yes, via webhooks: as soon as an event occurs (quote signed, payment received), the other tool updates within seconds, with no nightly batch.
What if an API changes? A maintenance contract (typically 10-20% of the initial cost per year) covers API changes and guarantees sync continuity.
Let's scope your project. Tell us your CRM, billing tool and priority flows, and we will price the connector and its ROI. 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.
