The verdict in three sentences
A connector between a CRM and an invoicing tool costs between 5,000 and 18,000 EUR in 2026, depending on the number of synced objects and flow directions. Manual double entry costs far more each year than the connector that removes it, with a typical payback of 6 to 12 months for an SME. Expect 3 to 6 weeks of project time and monthly maintenance of 150 to 400 EUR to absorb both apps' API changes.
What a CRM-invoicing connector covers
The goal is simple: a customer, quote, or invoice created on one side appears automatically on the other, without re-keying. Complexity comes from sync direction (upward, downward, bidirectional) and business rules (what to do if a customer already exists, how to handle quote statuses).
| Synced object | Direction | 2026 cost (EUR) |
|---|---|---|
| Customers / contacts | Bidirectional | 1,500 - 4,000 |
| Quotes | CRM to invoicing | 1,200 - 3,000 |
| Invoices and payment status | Invoicing to CRM | 1,500 - 4,500 |
| Products / pricing | Downward | 800 - 2,000 |
| Scoping and business rules | - | 1,000 - 3,000 |
| Testing and go-live | - | 1,000 - 2,500 |
iPaaS or custom development
In 2026, two paths for an SME. iPaaS platforms (Make, Zapier, n8n) are fast and cheap to set up but charge a monthly subscription that climbs with volume. Custom-built costs more upfront but stays stable over time and handles fine-grained business rules.
| Criterion | iPaaS (Make, n8n) | Custom-built |
|---|---|---|
| Initial setup | 3,000 - 7,000 EUR | 8,000 - 18,000 EUR |
| Monthly subscription | 30 - 200 EUR | 0 (hosting only) |
| Timeline | 2 - 4 weeks | 4 - 6 weeks |
| Complex business rules | Limited | Unlimited |
| Monthly volume supported | Up to ~10,000 operations | Unlimited |
| Maintenance | Partly included | 150 - 400 EUR/month |
Mini case study
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Sophie, director of a 25-person services SME in London, juggles a CRM and an invoicing tool. Two salespeople re-key every validated quote into an invoice: about 8 combined hours a week. She chooses a custom connector at 11,000 EUR, maintenance 250 EUR/month. Gain: 8 hours/week x 45 weeks = 360 hours/year at a 40 EUR loaded hourly cost = 14,400 EUR/year, not counting entry errors and invoicing delays. First-year total cost: 11,000 + 3,000 = 14,000 EUR. From year two, net savings exceed 11,000 EUR.
FAQ
How much is monthly maintenance? Between 150 and 400 EUR/month for a custom connector, or 30 to 200 EUR of iPaaS subscription. It covers both apps' API changes and flow monitoring.
Do you need two-way sync? Not always. Many SMEs settle for one direction (CRM to invoicing for quotes, invoicing to CRM for payments), cutting cost by 30 to 40%.
How long for a simple connector? 2 to 3 weeks with iPaaS for a single flow, 4 to 6 weeks custom for several objects with business rules.
What happens with a duplicate customer? You define a matching rule (by email, company number, or name) during scoping. This is a key point to settle before development to avoid production duplicates.
Is iPaaS reliable long-term? Yes for modest volumes and simple rules. Beyond 10,000 monthly operations or fine business logic, custom-built becomes more cost-effective.
Let's scope your project. Tell us your two tools (CRM and invoicing), the objects to sync, and an indicative budget, and we will price the right connector. 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.
