How to Keep Online and In-Store Inventory in Sync

If you run a wholesale business with a trade counter, you already know the answer isn't "hire someone to do it manually" and it isn't "buy a new ERP." But let's back up.
The moment it goes wrong
Most wholesale business owners don't look for an inventory sync solution because they think it’s probably a good idea. They go looking because something broke.
The story is almost always the same. A customer buys a product at the trade counter. Later that day, someone logs into the website to find an online order for that exact same product. It's now out of stock. The order has to be refunded. The fees are gone. And the customer who placed that order? They're not coming back. As found by KrispSystems, 69% of customers switch brands post-stockout, which is then also amplified by a negative social media review.
That's the overselling problem. And once you've experienced it, you'll do almost anything to stop it happening again.
The workarounds that don't actually work
The most common thing businesses do first is list only half their stock online. If you've got 10 units, you put 5 on the website. That way, you've got a buffer, right?
The problem is that this just moves the problem around. Now you're mentally keeping track of how many you've sold in-store versus what's left in the online buffer. In a busy trade counter, with multiple people on the till, that's impossible to maintain. And if a wave of online buyers comes through at the same time, you're now "out of stock" on the website even though you've got product sitting on the shelf. You've traded overselling for underselling.
Neither is a solution. Both cost you money.
Where most businesses go wrong when trying to fix it properly
The instinct, when manual workarounds fail, is to go big. Buy a new ERP. Rebuild the whole system. Start fresh.
This is almost always the wrong move.
New ERPs that promise to handle everything, including online sales, tend to lock you in. You get a shiny new system, but now you can't also sell on eBay, Amazon, or anywhere else without paying for more integrations or switching again. And there is disruption on the ground, retraining staff, migrating data, and changing the pick and pack workflow, which is enormous. It's expensive, it takes months, and it usually solves one problem while creating three more.
The better question isn't "how do we replace what we have?" It's "how do we build on top of what already works?"
Why things change when you hit 100 SKUs
If you're selling fewer than around 100 products, you can probably get away with manual processes for a while. It's not ideal, but it's survivable.
Once you go above that, the maths stops working. You can't keep track of that many SKUs across multiple channels in your head. You can't rely on spreadsheets updated twice a day. You need a system that updates automatically, in real time, every time a sale happens anywhere.
That's the threshold where the pain really starts.
So what does “problem solved” actually look like?
When inventory sync is working properly, you don't think about it. That's the point.
You sell a product at the trade counter, and the stock level updates online immediately. Or you sell something through your website, and it comes back into your ERP as a normal order, in exactly the format your team already knows how to process. Nobody has to log into a second system, and nobody has to manually adjust a number. You just... sell things, and the numbers stay correct.
That's what good looks like. Real-time visibility across every channel, without adding complexity on the ground.
How ShelfSync approaches this
ShelfSync sits on top of your existing ERP. The one you're already using. The one your team already knows.
It syncs your products out to whatever channels you sell on: WooCommerce, Shopify, Amazon, eBay, and more. Stock levels stay in sync automatically. And when an order comes in through any of those channels, it gets pushed back into your ERP as a normal order, ready to be picked and packed exactly the way you've always done it.
You don't rip anything out. You don't retrain your team. You don't migrate years of data. You just multiply where you can sell, and everything else stays exactly the same.
That's not a workaround. That's a system.
A real example: MD Thompson, Norwich
MD Thompson is an electrical wholesaler based in Norwich. They sell through a trade counter open to the public, and they needed a better online presence, one that was accessible to the public for browsing, but locked to account holders for actual purchasing (as is standard in wholesale).
Their old system was a vendor-built trade portal, clunky, inflexible, and unpopular with customers. But their ERP, and the pick and pack workflow built around it, worked fine. They didn't want to lose that.
ShelfSync synced their product catalogue from their ERP into a new WooCommerce store, including trade customer accounts and the customer-specific pricing that wholesale businesses depend on. Any order placed on the website comes back into the ERP as a standard order, indistinguishable from one placed through the old portal.
On the ground, nothing changed. Their staff process orders the same way they always have. But now MD Thompson has a modern, accessible trade portal they control, and the foundation to expand to other channels when they're ready.
Why hiring someone doesn't fix it
Sometimes people ask whether they could just hire someone to keep stock levels updated manually across platforms.
The honest answer: a human can't update stock fast enough to prevent overselling. A sale happens at the till in seconds. By the time someone logs in and makes the change, someone else may have already placed an order online.
And on top of that, a dedicated person to do this costs multiples of what a proper sync tool costs per month. You're paying more, getting less reliability, and you haven't actually built a system. You've built a dependency on someone doing a job that should never need doing.
The bottom line
If you're a wholesale business selling online and through a trade counter, the inventory sync problem has a clean solution. It doesn't require replacing your ERP. It doesn't require retraining your team. It doesn't require six months of disruption.
You keep the systems that work. You add the sync layer that connects them. And you stop losing sales, fees, and customer trust to a problem that's entirely solvable.
That's what ShelfSync is built to do. Find out more at shelfsync.app.
Still managing stock the hard way?
ShelfSync keeps your products, pricing, and stock in sync without the spreadsheet chaos. Less manual work, fewer mistakes, better control.