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UM Multistore Sync

Keeps inventory in step across your Shopify stores and explains every number the app sets.

Plans from Free to $797 help articleslast changed Oct 9, 2026

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Getting started

Four steps from installing the app to real-time sync running.

Before you start

  • The app is installed in both stores.
  • You have admin access to both stores.
  • The same variant has the same SKU in both stores.
  • No other app syncs inventory between these stores. The reason is further down under "No second sync app".

The four steps

The Overview page shows under "Getting started" what's done and what's next. The order is:

  1. Connect a second store
  2. Link locations
  3. Match variants
  4. Turn on real-time sync

The app works out whether a step is done from the actual state of your stores, not from a saved checkmark. Once all four are done, the section disappears.

The Overview page is the page the app opens on. In the menu, the app's name takes you there. The menu itself has five items: "Matching", "Sync", "Activity log", "Settings" and "Plan". "Stores" and "Locations" are pages under "Settings". At the top of that page, the "Setup" card has a row for each.

Connect a second store

  1. In the first store, open the app. On the Overview page, under "Getting started", click "Connect store". You're now on the "Stores" page.
  2. Under "Start here", click "Create code", then "Create code now".
  3. Copy the code with "Copy code". It's valid for 15 minutes and can be used exactly once.
  4. Switch to the other store, open the same app there and click "Connect store" there too.
  5. Under "I already have a code", click "Enter code".
  6. Paste the code into the "Invite code" field and click "Connect store".

Hyphens and upper or lower case don't matter. You always enter the code in the other store, never in the one where you created it.

After that, the "Stores" page shows your sync group. Later you find it under "Settings" → "Stores". You can use every feature from any store in the group. It doesn't matter which one you're in.

Below that, under "What's next", the page names the next open step with the reason and a button. It's the same one the Overview page shows as next under "Getting started". Once all four steps are done, the section is no longer there.

If the code isn't accepted

  • The code has expired. It's valid for 15 minutes. Create a new one.
  • This code has already been used. Each code works exactly once. Create a new one.
  • This is this store's own code. You're still in the store where you created it. Enter it in the other store.
  • This store already belongs to a group. A store can only be in one group.
  • Too many failed attempts. After ten failed attempts within 15 minutes, wait a few minutes and try again.

If you created a code but no longer have it, just create a new one.

Link locations and match variants

Next, you decide under "Settings" → "Locations" which locations belong together. The "Link locations" button under "What's next" takes you straight there. Then you start matching variants by SKU on the "Matching" page. Both have their own articles: "Linking locations" and "Matching variants".

Turn on real-time sync

  1. Open "Settings".
  2. Under "Sync", pick your rule for "Which inventory wins" and click "Save rule and schedule".
  3. Under "Real-time sync", tick "No other app syncs inventory between these stores."
  4. Click "Sync and turn on real-time sync".
  5. The app first syncs all inventory using your rule. You can follow the progress on the "Sync" page. Once that sync is done, real-time sync shows as "On".

The sync beforehand isn't a detour. Real-time sync sends changes. If the stores started from different numbers, the difference would stay forever.

No second sync app

Two apps that sync the same stores pass every change on twice. A sale then lowers the other store twice, the apps react to each other, and inventory counts down in all stores.

So turn the other app off before you run a sync here or turn on real-time sync. You can connect stores, link locations and match variants beforehand. The app writes nothing to your stores while you do.

Shopify itself shows whether another app still changes inventory: open a variant in your Shopify admin and look at its adjustment history. Each change lists the app or staff member behind it.

If one is still running after all, the app can only limit the damage. It pauses an affected SKU as soon as the same change keeps coming back with no order behind it (see "Notices and what to do"). By then, inventory has already been miscounted. In a test on October 6, 2026 it paused after the first round. By then, inventory was at 140 instead of 35 in both stores. Turning the other app off is the only safe protection.

If real-time sync won't turn on

The app shows the reason right away below the button, or under "Real-time sync wasn't turned on" in Settings if the sync beforehand failed. The most common reasons:

  • The checkbox "No other app syncs inventory between these stores." isn't ticked.
  • No location link is set up yet. Link the locations under "Settings" → "Locations".
  • A connected store has more matched SKUs than its plan includes. The reason names the store. Choose a plan that fits on the "Plan" page in that store.
  • A sync is running right now, for example the scheduled one. Wait until it's done. The "Sync" page shows the progress. Then click "Sync and turn on real-time sync" again.
  • The safety brake stopped the sync that runs before switching on. Check whether one of the stores is empty or incomplete right now. Real-time sync stays off until that's resolved.