The verdict in three sentences
An API connector between your business application and Xero or QuickBooks Online costs between EUR 5,000 and 16,000, depending on how many flows you sync and how well errors are handled. For an SME re-keying 600 invoices a month, it saves 25 to 40 hours of data entry monthly and removes most posting errors. With maintenance at EUR 120 to 350 per month, the investment usually pays back in 6 to 14 months.
What an accounting connector must sync
The CFO of a Dublin technical services SME watches the accounts assistant re-key every invoice issued from the business app each month: number, customer, net and VAT amounts, revenue account, due date. At 3 to 4 minutes per invoice, 600 invoices mean 30 to 40 hours. A serious connector covers several flows.
| Flow | Direction | Xero | QuickBooks Online | Complexity |
|---|---|---|---|---|
| Sales invoices | App to accounting | Native REST API | Native REST API | Low |
| Contacts (customers and suppliers) | Two-way | Native API | Native API | Medium |
| Tracking categories and classes | App to accounting | Tracking categories | Classes and locations | Medium |
| Payment status | Accounting to app | Webhooks | Webhooks or polling | Medium to high |
| Credit notes and voids | App to accounting | Native API | Native API | Medium |
| PDF attachments | App to accounting | Files API | Attachable API | Low to medium |
Both platforms have well-documented REST APIs, but rate limits (60 calls per minute on Xero, 500 per minute on QuickBooks) require batching for high volumes.
Accounting API integration cost in Dublin in 2026
| Scope | Content | Budget (excl. VAT) | Timeline |
|---|---|---|---|
| Simple export | Sales invoices, once a day | EUR 5,000 to 7,000 | 2 to 3 weeks |
| Standard sync | Invoices, credit notes, contacts, attachments | EUR 7,000 to 10,000 | 3 to 5 weeks |
| Full sync | Standard + tracking + payment status | EUR 10,000 to 13,000 | 5 to 7 weeks |
| Multi-entity | Full + several Xero or QuickBooks organisations | EUR 12,000 to 16,000 | 6 to 8 weeks |
| Maintenance | Monitoring, API changes, rejects | EUR 120 to 350 / month | Ongoing |
| iPaaS tools (Make, Zapier) | Alternative for very simple flows | EUR 50 to 350 / month | 1 to 2 weeks |
iPaaS suits a single, low-volume flow. Above 300 invoices a month, with posting and tracking rules, a coded connector is more reliable and easier to audit.
Error handling, the most underestimated item
A connector is only as good as its handling of rejects: unknown contact, missing VAT rate, locked period, duplicate invoice number. Require a queue of rejected entries, an email alert to the accountant, automatic retry after correction and a log of every sync. With Ireland preparing e-invoicing under the EU ViDA package (domestic B2B e-invoicing phased in from 2028, with large companies starting earlier), the connector should be designed to support structured formats such as Peppol UBL.
Mini case study
Ciarán, CFO of an industrial maintenance SME in Dublin (EUR 11 million revenue, 600 invoices a month), orders a full sync to Xero for EUR 11,500, with maintenance at EUR 200 per month. Before: 3.5 minutes per invoice, 35 hours a month of re-keying, plus about 2% posting errors fixed at month end, 6 more hours. After: 3 hours a month checking rejects. Gain: 38 hours per month, at EUR 40 loaded per hour, EUR 1,520 per month. Net of maintenance: EUR 1,320 per month. Payback: 11,500 / 1,320 = about 9 months. Month-end close also moves from day 12 to day 7.
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FAQ
Xero or QuickBooks: which is easier to connect?
Both are straightforward. Xero's tighter rate limit makes high-volume syncs slightly more complex, while QuickBooks requires more care with tax codes across regions.
What if the vendor changes its API?
That is what EUR 120 to 350 per month of maintenance covers: tracking announcements and updating the connector before the old version is retired.
Will the connector be ready for e-invoicing?
It should be. Budget EUR 1,500 to 3,500 extra for Peppol UBL support when your obligation date is confirmed.
Should our external accountant be involved?
Yes, to validate the chart of accounts, VAT rules and tracking. Plan 2 to 4 hours of their time during scoping.
Can we sync in real time?
Yes, both platforms support webhooks. For large batches, a sync every 15 minutes is more robust against rate limits.
Let's scope your project. Tell us your application, accounting software and volumes: we will price a connector between EUR 5,000 and 16,000, delivered in 2 to 8 weeks. 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.
