The verdict in three sentences
An API integration between your business app and an ERP is budgeted in 2026 at 8,000 to 25,000 EUR, the range driven mostly by the number of synced objects (customers, items, orders, journal entries) and the sync mode. Plan for 3 to 6 weeks of development, a possible ERP-side API license of 0 to 3,000 EUR/year, and 200 EUR/month monitoring. The 15%/year maintenance on project cost is the most underestimated line: it is what keeps the flow alive over time.
What drives the price
Connector pricing is not tied to page count but to the number of flows and objects kept in sync, and to the complexity of business rules (mapping, deduplication, multi-rate VAT, currencies).
| Scope | Synced objects | Timeline | 2026 price (EUR) |
|---|---|---|---|
| Simple connector | 1-2 (e.g. customers + invoices) | 2-3 wks | 8,000 - 12,000 |
| Standard connector | 3-4 (customers, items, orders, stock) | 3-4 wks | 12,000 - 18,000 |
| Advanced connector | 5+ plus journal entries | 4-6 wks | 18,000 - 25,000 |
| Multi-company / multi-site | 5+ x N entities | 6-8 wks | 25,000 - 40,000 |
| Historical migration | +data migration | +1-2 wks | +3,000 - 8,000 |
On licensing: some ERP APIs are included in the pack, while others (advanced web APIs) can reach 1,500 to 3,000 EUR/year. That recurring cost belongs in your 3-year TCO.
Real-time or nightly batch: the structural choice
The sync mode changes build cost, robustness and user experience. A webhook (event push) reacts within a second but demands careful error handling; polling or a nightly batch is cheaper but introduces lag.
| Criterion | Webhook / real-time | Polling / nightly batch |
|---|---|---|
| Data freshness | < 5 seconds | 1 to 24 hours |
| Build cost | 12,000 - 25,000 EUR | 8,000 - 15,000 EUR |
| ERP server load | Low, event-driven | High at sync windows |
| Error handling | Queue + replay | Next batch recovery |
| Typical use case | E-commerce stock, availability | Accounting consolidation |
| Monitoring required | Mandatory (200 EUR/mo) | Recommended |
For replays, a serious connector logs every call, queues failures and retries with exponential backoff: without it, a brief ERP outage silently drops orders.
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Mini case study
Hugo, IT director of a 60-person distribution SME in Berlin, wants to sync his field order-taking app with the ERP. Scope: customers, items, orders and stock (4 objects), real-time for stock, batch for accounting. Accepted quote: 16,000 EUR build, 900 EUR/year API license, 200 EUR/month monitoring, 2,400 EUR/year maintenance (15%). Payoff: eliminating 20 hours/month of re-keying at 40 EUR, i.e. 9,600 EUR/year, plus the end of undetected stockouts. The connector pays for itself in just over 18 months.
FAQ
Do I need an extra ERP-side license? It depends on the vendor: some APIs are included, others (advanced web APIs) can cost 1,500 to 3,000 EUR/year. Check before signing, it weighs on TCO.
How long for a first connector? Between 3 and 6 weeks for 3 to 5 objects, including interface acceptance testing. A single-object connector can ship in 2 weeks.
Is real-time always better? No. For accounting consolidation, an 8,000-15,000 EUR nightly batch is plenty. Real-time is justified for stock or product availability.
What does the 15% maintenance cover? Tracking ERP version upgrades, fixing broken mappings, adding fields and monitoring replays. It is the line that prevents a silent failure after 6 months.
Can an existing connector be reused? Yes for standard ERPs, but each client's configuration (custom fields, VAT rules) needs a specific 2-5 day mapping effort.
Let's scope your project. Tell us your ERP, the number of objects to sync and the mode (real-time or batch): we will price the connector and maintenance. 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.
