How Sumtracker fixed inventory sync from 3PL to Amazon

Industry: International eCommerce (Shopify DTC + Amazon FBM) with 3PL Fulfillment

Sales Channels:

• Shopify (two stores: UK and DE)
• Amazon (UK & Germany – FBM)

Fulfillment Setup:

• They work with a 3PL to ship both Shopify and Amazon orders
• 3PL stocks at two warehouses: UK and EU
• 3PL pushes inventory updates to Shopify
• Incorrect inventory was syncing to Amazon (combined inventory for both warehouses)

About the Brand

Built on the belief that creativity should be part of everyday life, this UK-based brand has turned the simple joy of making into something truly special.

Their flagship DIY pottery kits have brought hands-on creativity into thousands of homes, helping people slow down, get messy, and create something that’s entirely their own.

What started with a single clay kit has grown into a full range of creative products, including sculpting tools, paints, sealers, and other craft materials, all designed to help customers unwind and explore their imagination.

The brand has tapped into a cultural shift toward mindful, screen-free hobbies and experiential gifting, making it a favorite among both casual hobbyists and design-forward consumers.

They sell through localized Shopify storefronts in the UK and Germany, along with a growing presence on Amazon, allowing them to reach customers across Europe.

With thoughtfully packaged kits, clear instructions, and a strong focus on brand experience, they’ve successfully positioned themselves at the intersection of creativity, lifestyle, and eCommerce.

The Challenge

As the brand expanded across multiple markets, keeping inventory accurate across regions became difficult. They operated two separate Shopify stores, one for the UK and another for Germany and sold through Amazon FBM for both countries.

While their 3PL was reliably pushing stock updates to Shopify, the issue began once that inventory reached Amazon.

Instead of keeping stock data separate for each region, the system was merging inventory from both the UK and EU warehouses and pushing the same combined quantity to both Amazon stores.

This created a disconnect between what was available in each warehouse and what Amazon displayed, leading to:

• Inflated stock levels on Amazon UK and DE
• Risk of overselling when one region ran out of stock
• Incorrect order routing, causing delays and fulfillment headaches
• No way to control which inventory went to which Amazon store

On top of that, some SKUs differed between Shopify and Amazon, making it even harder to sync listings properly without manual workarounds.

The team needed a solution that could sit between Shopify and Amazon, one that would manage regional inventory, support SKU mismatches, and give them more control over what got pushed, where, and when.

The Sumtracker Solution

To resolve the inventory disconnect between Shopify and Amazon, the brand turned to Sumtracker to act as the central control layer, sitting between their Shopify stores and Amazon FBM accounts.

This allowed them to maintain their existing workflow (where their 3PL updates stock on Shopify), while giving them full control over what inventory gets pushed to which Amazon store, with speed, accuracy, and flexibility.

Here’s how Sumtracker solved the problem:

1. Shopify Remained the Source of Truth

There was no need to change their fulfillment setup. Sumtracker was configured to pull inventory directly from Shopify, using the live data that their 3PL was already pushing.

This meant the brand didn’t have to modify anything on the backend. Sumtracker mirrored Shopify and took care of syncing to Amazon.

2. Created Separate Warehouses for UK and Germany

The biggest issue was that inventory from both the UK and EU warehouses was being treated as one.

Sumtracker solved this by treating the two Shopify store locations as independent warehouses, one for the UK and one for Germany.

Each was linked to its respective Amazon FBM store, ensuring regional inventory was kept separate and correctly displayed.

3. Enabled Fast, Reliable Sync to Amazon

Once the inventory was updated in Sumtracker, it was pushed to Amazon, keeping stock levels consistently up to date.

This helped eliminate overselling and made sure customers saw accurate availability, even during high sales periods.

4. Mapped Mismatched SKUs Using Bundles

Some product SKUs were different between Shopify and Amazon, which had previously made syncing tricky.

Sumtracker’s bundling feature allowed the team to link these SKUs to the same underlying inventory.

No matter which SKU received the order, the stock would update correctly on both platforms.

5. Added Buffer Controls with Close at Quantity

To prevent accidental overselling, the brand used Sumtracker’s close-at-quantity feature, essentially a custom buffer per SKU.

For example, if they set a close at quantity of 50, Sumtracker would stop pushing inventory to Amazon once stock dropped to that level, showing zero instead.

This gave the team extra breathing room while still selling safely.

Results After Implementing Sumtracker

After implementing Sumtracker, the brand saw immediate improvements in how inventory was managed across regions, channels, and SKUs.

Here’s what improved within the first few weeks of rollout:

• Overselling reduced by 99% within the first 30 days.
• 320+ SKUs synced across two Shopify stores and two Amazon marketplaces
• 112 mismatched SKUs mapped using Sumtracker’s bundle feature  without changing product listings
• 75% reduction in manual inventory checks by operations and support teams
• Zero disruptions to 3PL process, Shopify stayed the single source of truth
• Enabled smooth scaling across United Kingdom and Germany, with plans to expand to more marketplaces using the same setup

What the Team Says

“Sumtracker has made it so much easier to manage our inventory across regions. We finally have control over what gets pushed to Amazon UK and Germany without changing how we run our Shopify stores. The SKU mapping and sync logic just work, and it’s saved us a lot of time.”

— Operations Lead, DTC Craft & DIY Brand

Sumtracker Impact at a Glance

Conclusion

For this UK-based craft and DIY brand, inventory updates, SKU mismatches, and marketplace syncs failed to align.

But with Sumtracker, they found a solution that didn’t just fix the problem, it fit perfectly into their existing setup.

By syncing accurate stock from Shopify to Amazon UK and Germany, enabling real-time updates, and solving SKU mapping challenges with bundles, Sumtracker gave the team the control and confidence they needed to scale without the stress.

No manual workarounds. No disrupting the 3PL. Just clean, reliable inventory sync and a system ready to grow with them.

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