Mortar vs. Lightspeed's Native Shopify Integration

The native integration manages inventory through adjustments rather than transactions — and adjustments are inherently fragile. They can fail silently or apply out of sequence, and the only way to investigate is to check the inventory history of each affected product one by one — there’s no transaction tying a sale to the inventory movement across an entire order. The native integration also requires both a matching SKU and product handle to link products between platforms — a significant amount of manual work to set up correctly, and any products that aren’t linked hold separate inventory counts on each side, compounding the problem. Retailers report seeing 3 items show as 6, or customers checking out products that are actually out of stock.

Mortar matches by SKU, UPC, or EAN alone and includes a live product linking dashboard so you can see which products aren't connected between Lightspeed and Shopify — and fix gaps before they turn into inventory problems.

Shopify automatically archives fulfilled orders — and the native integration won’t import archived orders. Orders with deleted, unlinked, or custom products, or from third-party fulfillment apps are also silently skipped, with no error or alert. And simply editing a product in Shopify can delete the original product ID and trigger the same failure — meaning a routine catalog update can silently start dropping orders.

Mortar imports orders regardless of archived status, flags unlinked or deleted products rather than dropping orders, and shows a live list of unlinked products so you can fix gaps before they cause problems.

Every online order is recorded against a single designated Shopify register in Lightspeed, regardless of which location actually fulfilled it. Inventory deducts from the fulfillment locations — but no transaction is created there. And there’s a critical gap: the native integration does not sync returns or exchanges. With return rates typically running 20–35%, that creates a steady, compounding drift in inventory accuracy. For BOPIS, the problem is more immediate: the store team at the pickup location has no transaction to work from. The order is in the download store. The inventory moved; but the fulfillment workflow is sideways.

Mortar creates a transaction at the fulfilling location — whether ship-from-store or BOPIS — and syncs returns and exchanges automatically. Your team can manage order fulfillment, and your per-location records stay accurate and auditable.

When something breaks at the seam between Lightspeed and Shopify, it’s not always obvious which platform is the source — and it’s genuinely difficult to diagnose without knowing both sides equally well. Retailers commonly report days of back-and-forth between two support teams before finding resolution.

Mortar’s support team works exclusively with Lightspeed and Shopify merchants and is consistently praised for knowing how both platforms operate. One team, one place to go.

If you run a single location, have a consistent product catalog across both platforms, and process few online returns — the free integration may be enough to start. If you’re already running into the issues above, or expect to as you grow, Mortar is built for exactly that situation.

Inventory doubling is one of the most consistently reported issues with the native integration. It typically happens because products aren't linked between Lightspeed and Shopify so inventory gets duplicated for the same product, rather than synced. The native integration requires both a matching SKU and product handle to link products — any gap in that setup leads to separate counts on each side. Mortar matches by SKU, UPC, or EAN alone, maintains one accurate count across both platforms, and surfaces unlinked products so you can fix gaps proactively.

No. Returns processed in Shopify don’t automatically update inventory in Lightspeed — you’ll need to adjust manually. With online return rates typically running 20–35%, unsynced refunds create a steady, compounding drift in inventory accuracy that’s difficult to catch and time-consuming to correct. Mortar syncs refunds, exchanges, and order edits automatically.

When inventory falls out of sync, Shopify continues showing products as available based on its own stale count. Until the sync catches up — or someone manually corrects it — customers can place orders for items you don’t actually have. Mortar syncs inventory in real time and catches edge cases like refunds and order edits that the native integration misses.

Most likely the orders are archived — Shopify automatically archives fulfilled orders, which the native integration won’t import. Orders with deleted or unlinked products, custom line items, or from third-party apps are also silently skipped. Mortar handles all of these.

Inventory deducts from the correct location, but every sale records against a single Lightspeed register — so the store team at the fulfilling location has no transaction to work from. For BOPIS, the pickup team has no visibility into the order; it’s sitting in the download store, not theirs. Returns and exchanges also go unsynced, compounding the drift over time. Mortar creates a transaction at the fulfilling location and syncs returns and exchanges automatically, so your team can act on orders and your records stay accurate.

Cross-platform issues are genuinely difficult to diagnose — the problem could originate on either side, and resolving it requires knowing how both platforms interact. Retailers commonly report days of back-and-forth before finding resolution. Mortar’s support team works exclusively with Lightspeed and Shopify merchants, owns the integration end-to-end, and is consistently praised for knowing how both platforms operate.

For single-location stores with simple, fully-linked catalogs and low return volume, the native integration may be enough. For anyone running multiple locations, meaningful returns, BOPIS, or a product catalog that doesn’t perfectly mirror between Lightspeed and Shopify — the cost of Mortar is typically recovered quickly in time saved on manual corrections and oversells avoided. Start a free trial to see how it handles your specific setup.