In short: an integration between your online store and Exact Online books orders, customers, payments and stock into your accounting automatically. A standard connector costs €10 to €60 per month and works for 80% of online stores. Custom work on the Exact Online API costs €3,950 to €25,000 and is needed for B2B price lists, multiple warehouses or non-standard VAT.
What you want to synchronize
Before you pick a connector, decide exactly what has to flow back and forth. Most online stores need 3 of these 6 flows; the other 3 decide whether you need custom work.
- Orders to sales invoices or sales orders. In Exact Online Accounting every order becomes a sales invoice. In Exact Online Trade you can also create sales orders, with picking, delivery and invoice as separate steps.
- Customers to accounts (debtors). Creating new customers, recognizing existing ones by email address or Chamber of Commerce number, updating addresses and VAT numbers. Sloppy matching produces 3 versions of the same customer.
- Payments to bank reconciliation. Mollie, Adyen or Shopify Payments pay out net of fees. A good integration books gross revenue, payment fees and the payout separately, so the bank reconciles.
- Products and stock. Items from Exact to the store (or the other way), stock levels after every sale and delivery back to the store. Trade edition only.
- VAT. 21%, 9%, 0%, reverse charge for EU businesses, OSS for EU consumers, export outside the EU. Every line has to land on the right VAT code.
- Returns and credit notes. A return in the store becomes a credit note linked to the original invoice, with a stock correction if the product comes back.
For each flow write down: direction, frequency (real time, hourly, daily) and which system is the source of truth. That document is half your integration.
Standard connector or custom API integration
| Standard connector | Custom API integration | |
|---|---|---|
| Examples | Webwinkelfacturen, Combidesk, xCore, connectors from the Exact App Center | Your own integration on the Exact Online REST API, built by a developer or studio |
| Cost | €10 – 60 per month per store, sometimes a one-off setup of €100 – 500 | €3,950 – 25,000 one-off, plus management from €450 per month |
| Lead time | 1 day to 1 week | 2 to 8 weeks |
| Coverage | Orders, customers, invoices, payments, basic stock | Everything the API allows: orders, price lists, warehouses, projects |
| VAT logic | Standard situations (NL, EU, export) | Every rule you need, including OSS per country |
| Discounts and shipping | Usually fine, sometimes as an order-level discount | Per line, per VAT rate, booked the way you want |
| Multiple stores or warehouses | A subscription per store, warehouses limited | One integration for everything |
| Error handling | Email on failure, fix by hand | Retry, queue, dashboard, alert in Slack or Teams |
| Ownership | Subscription, data with the vendor | Code and logs are yours, runs in your environment |
| Suited for | 80% of B2C stores with standard VAT | B2B, multiple warehouses, high volumes, non-standard processes |
The rule of thumb: start with a connector if your situation is standard. When you hit the third workaround (manual corrections, duplicate customers, VAT differences at the accountant), custom is cheaper than muddling on.
Costs and lead time
Standard connector. €10 to €60 per month, depending on order volume and features. Setup takes half a day: connecting, assigning ledger accounts and VAT codes, checking a test order. Budget €500 to €1,500 if your builder or accountant does it.
Custom. An integration of 1 online store with Exact Online, covering orders, customers, payments and credit notes, costs €3,950 to €7,500 and is ready in 2 to 4 weeks. Add stock, multiple warehouses, B2B price lists and a second channel (Bol.com, a B2B portal) and you are at €7,500 to €15,000 and 4 to 8 weeks. An integration layer connecting online store, Exact, WMS and a marketplace starts at €15,000.
Then there is management: monitoring, repairs after API changes, adjustments for a new VAT rate or product group. Budget €450 to €950 per month, or a few hours a month if you keep it in-house.
Lead time rarely depends on the build and almost always on preparation: are ledger accounts, VAT codes and item codes in Exact in order, and is it clear which system is the source of truth?
Pitfalls: VAT, discounts, returns, warehouses and B2B price lists
These are the 7 points where integrations break down in practice. Ask about them before you sign.
- VAT codes. An online store knows 'VAT 21%', Exact knows dozens of VAT codes, each with its own ledger account and return box. An order to a German consumer above the OSS threshold (€10,000 EU-wide) gets German VAT; to a Belgian business with a valid VAT number it is reverse charged; to a Swiss customer 0% export. Have the integration book a test order per situation and have your accountant check the return.
- Discounts. Discount codes, tiered discounts and free shipping arrive at order level in online stores, while Exact wants them per line. Spread the discount proportionally across the lines, with the correct VAT rate per line. Otherwise your revenue per product group is wrong.
- Shipping costs. Book as a separate line on its own ledger account, with the VAT rate that follows the goods.
- Returns and partial returns. A credit note must reference the original invoice, credit the right lines and correct stock if the product comes back. Many connectors turn a return into a loose negative invoice, and then your VAT return no longer adds up.
- Payment fees and payouts. Mollie pays out net per day or week. Book gross revenue, fees and payout separately, otherwise your bank stays unreconciled.
- Multiple warehouses. A shop, an external fulfillment center and a dropshipper: Exact Online Trade Advanced or Premium supports multiple warehouses, most connectors do not. Decide which warehouse drives the online store stock.
- B2B price lists and payment terms. Customer-specific prices, tiers and 'on account' at 30 days: in Exact they live with the account and the price list, in the store with the customer group. For a B2B online store this is the core of the integration, and almost always custom.
And the quiet pitfall: duplicate customers. Matching on email address alone gives a company with 3 buyers 3 debtors. Match on Chamber of Commerce or VAT number, with email as the fallback.
Shopify, WooCommerce or a custom platform
Shopify. Strong, stable API with webhooks on every order change. Shopify Payments reports per payout, which makes reconciliation easy. Connectors abound; custom work builds on the Admin API. Watch out: Shopify rounds VAT per line, Exact per invoice, and that produces cent differences your integration has to absorb.
WooCommerce. Open REST API, everything adjustable, but your data quality depends on plugins. VAT settings in WooCommerce are error-prone; check them before you connect. Webhooks work, but are less reliable than Shopify's, so a good integration also polls for orders periodically.
Custom platform (Next.js with Medusa, Saleor or your own backend). You decide what orders look like, so you build the data model the way Exact wants it from the start: lines with VAT code, discount per line, warehouse per line. The integration gets simpler, not more complex. For B2B portals with Exact as the source of prices and stock, this is the most robust route.
Which platform suits you is covered in Shopify vs WooCommerce. For retail and e-commerce the accounting integration is a standard part of our online store projects.
The Exact Online API: limits and what they mean
The Exact Online REST API is mature and well documented, with a few rules your integration has to respect:
- Rate limits. By default 60 calls per minute and 5,000 per day per company per app. For a store with 200 orders a day that is plenty, provided you bundle smartly: 1 order easily takes 3 to 5 calls (look up the account, check the item, create the invoice). A naive integration that fetches everything every minute hits the limit within an hour.
- Sync endpoints and webhooks. For stock and items you use the sync endpoints, which return only changes since the last run. Webhooks exist for accounts, items and sales orders, among others.
- OAuth 2.0 and tokens. Access tokens expire after 10 minutes, refresh tokens after 30 days without use. An integration that sits idle for 6 weeks (holidays, a test environment) has to be re-authorized.
- App Center. A production integration has to be registered as an app with Exact. For an integration only you use, that can be your own app; if you offer it to others, you become a partner.
- Editions. Sales orders, stock, price lists and warehouses live in Exact Online Trade, not in Accounting. Check your subscription before you commission an integration that needs those endpoints.
What this means: a good integration is event-driven (a webhook from the store triggers the booking), bundles calls, keeps a queue during outages and logs every booking with the Exact number attached. That way you find an error in 1 minute instead of in the VAT return.
Step-by-step plan
- Week 1: inventory. Flows, direction, frequency, source of truth. Ledger accounts, VAT codes and item codes in Exact in order. Decide: connector or custom.
- Week 2: configure or build. Configure the connector, or build the custom integration against a test company in Exact.
- Week 3: test with real scenarios. Dutch consumer, EU business reverse charged, EU consumer OSS, export, discount, partial return, payment through Mollie. Accountant reviews.
- Week 4: go live and check. Reconcile daily in the first week, then weekly. Only after the first VAT return is the integration truly signed off.
RABZI estimate: an Exact Online integration from RABZI starts at €3,950 excl. VAT for 1 integration (online store to Exact: orders, customers, payments, credit notes, live in 2 to 4 weeks), from €9,500 for an integration layer with 3 systems (online store, Exact and for instance a WMS or Bol.com) and from €24,500 for middleware with EDI or Peppol. Management and monitoring from €450 per month. Code, logs and the app registration are in your name. See integrations, APIs and backend or the full pricing.
Frequently asked questions
How much does an Exact Online integration with my online store cost? A standard connector costs €10 to €60 per month plus half a day of setup. A custom integration on the Exact Online API costs €3,950 to €7,500 for 1 online store with orders, customers, payments and credit notes, and €7,500 to €15,000 when stock, multiple warehouses or B2B price lists are added.
Does an Exact Online integration work with Shopify and WooCommerce? Yes, standard connectors are available for both platforms and both have an API for custom work. Shopify has the most stable webhooks and payout reporting; with WooCommerce data quality depends on your VAT settings and plugins. Check those before you connect.
Do I need Exact Online Trade for a stock integration? Yes. Sales orders, items with stock, price lists and warehouses live in Exact Online Trade. With Exact Online Accounting you connect orders as sales invoices, customers and payments, but no stock. Check your subscription before you commission an integration.
How does an integration handle VAT on EU sales? A good integration books each situation on the right VAT code: Dutch VAT for Dutch customers, reverse charge for EU businesses with a valid VAT number, OSS at the destination country's rate for EU consumers above the €10,000 threshold, and 0% export outside the EU. Test every situation with a trial order.
Conclusion
An integration between your online store and Exact Online saves hours of manual work every week and prevents errors in your VAT return, provided VAT, discounts, returns and stock are set up properly. Start with a connector if your situation is standard; go custom as soon as B2B, multiple warehouses or high volumes come into view. Want to know which route fits your store? Book an intro call and you will have an estimate with a fixed price and date within 2 business days.