What connects to Shopify

Shopify runs the storefront: the catalogue, the checkout, the paid order, the refund, the customer waiting for a tracking number. Most of what sits behind it does not live in Shopify. Stock, invoices, the ledger, and your tax advisor’s books sit elsewhere, and by default Shopify tells none of them what happened.

Three kinds of systems get connected. ERPs such as SAP Business One, NetSuite, Business Central, or weclapp take orders as proper sales documents and send item master data, stock, and fulfilment status back, as in Shopify to NetSuite. Accounting takes the sale and the payout as bookings, which for DACH merchants usually means Shopify to DATEV or Shopify to sevDesk. Marketing platforms take customers, orders, checkouts, and consent state, as in Shopify to Klaviyo.

Where Shopify integrations break

A variant SKU is not an item number. Every Shopify SKU has to resolve to exactly one ERP item. Typos, renamed variants, and bundles that are one product in Shopify but several lines in the ERP are where syncs post to the wrong item. Unmatched lines are held, never guessed.
Guest checkouts have no stable identity. Without a deliberate match rule, a repeat buyer becomes a new customer, debtor, or profile on every order.
The payout is not the revenue. Shopify Payments settles net of fees, days later, in a batch spanning many orders. Sale and settlement are separate bookings joined by a clearing account.
Tax lines are not tax codes. Shopify records the tax it collected; the target needs a tax key, a tax type, or a VAT posting group. Domestic sales, EU distance sales under OSS, reverse charge, and exports each map differently.
The API is metered. Shopify enforces cost-based GraphQL and leaky-bucket REST limits. A launch-day sync or a full catalogue push hits them, so writes have to be queued, paced, and retried.