Custom software for syncing inventory across sales channels
Two channels selling the last unit at the same moment is not bad luck but a design flaw. As long as each channel holds its own copy of the stock and updates it with a delay, the question is not whether it will go wrong but how often.
Where synchronisation breaks down in practice
The core of the problem is delay. A marketplace fetches your stock on its own schedule, your webshop updates after an order, and the shop records the sale at checkout. Between those moments there is no shared truth, only a set of copies that each believe something different.
With one unit in stock, that delay becomes visible. Two customers can order at the same time because both channels still show one available. This is overselling, and its cost lies not in the stock itself but in the cancellation, the customer contact and the review that follows.
On the consumer side there is little room to solve this by waiting. If no delivery time has been agreed, the statutory period of thirty days applies. And the information you give about availability must be accurate: scarcity indicators must not be misleading, and withholding or obscuring material information is an unfair commercial practice.
That means the solution is not to show lower stock everywhere and hope it works out. It means you must determine what the truth is, who may change it, and at what moment a unit moves from available to reserved.
How we build this
The core is that there is one place that knows the stock and that all channels are derived from it. As soon as two systems are both allowed to decide, it is only a matter of time.
Which system knows the actual stock. All channels display a derived figure from it, not their own version.
The moment a customer orders, the unit moves from available to reserved, before the rest is updated.
Directly wherever possible, with a fallback if a channel only polls periodically.
A check that compares channel stock with actual stock, because silent discrepancies build up.
What the software actually does
One source of truth with reservations carries the whole setup. What else you need depends on the number of channels and how quickly they can be updated.
One source of truth for stock
Free stock, reserved and incoming kept apart, because those three are not the same and are often lumped together.
Reserve on order
The unit is taken as soon as someone orders, not only once the order is processed. That is where most of the risk lies.
Buffer per channel
A channel that updates slowly gets a margin, so the delay does not lead to overselling.
Feedback per channel
Visibility of whether a channel has processed the update, because a sent notification is not a processed notification.
Flagging discrepancies
A daily comparison between what a channel shows and what is actually on the shelf.
Bundles and variants
A set of three items affects three stock levels. If you don't account for that, you end up selling sets you cannot make.
Who we build for
Who this affects varies by business. Four situations.
Webshops with marketplaces alongside
Each platform has its own rules on how quickly stock may be updated and what happens when an order is cancelled.
Retailers with shop and online
The shop floor sells without the webshop knowing, and that is the hardest direction.
Wholesalers
They supply customers who also display stock, which lengthens the chain of copies.
Businesses with unique items
With second-hand or one-off items, every unit is the last one, and then every second of delay counts.
Test your idea first: a working prototype in 1 day
With OneDayBuild, we turn your idea into something tangible in one day for €1,150, so you can see whether further development is worth the investment. Decide to go ahead with the full build? Then we credit the full cost.
Explore OneDayBuild →Technology and integrations
Channels get added, interfaces change and platform rules are revised. Channels, buffers and rules should be configurable rather than hard-coded.
For shop and warehouse staff who want to push corrections to all channels directly, there is our app for multichannel stock synchronisation.
If you are specifically looking at bol.com, Amazon and other marketplaces, with rules per platform, see our app for a marketplace integration with your stock.
Why Appfront
Copies do not decide
As soon as two systems both get to decide what is free, overselling follows. We designate one source.
Reserving matters more than updating quickly
Removing the unit at the moment of ordering solves more than any speed-up of the synchronisation.
A sent notification is not a processed one
Channels don't always confirm. Without feedback you assume it's correct while the screen shows something else.
Your availability text must be accurate
Scarcity indicators must not mislead. That is one more reason to make sure the numbers are right.
Security and privacy
Stock data says something about your revenue, your purchasing and your margins, and integrations with marketplaces contain keys that give access to your sales accounts. We set up role-based access, store integration keys separately from everything else, and log who views what. Integrations run through secure connections to your existing software.
For this topic, the reliability of the moment is the crux. In a dispute over a cancelled order, the question is what the system knew as free stock at that moment. We record every stock movement in an unalterable way with time, source and person, and make a correction a visible correction alongside the original entry. How we handle security ourselves is set out in our information security policy.
Frequently asked questions about stock synchronisation
That each channel keeps its own copy of the stock and updates it with a delay. Between two updates there is no shared version of the truth. With one unit in stock, two customers can then order at the same time, because both channels still show it as available at that moment.
To a degree. The structural fix is to reserve stock at the moment of ordering, so the unit is gone before synchronisation catches up. Speeding things up narrows the window, but it does not close it.
A margin you hold back on channels that update slowly: for example, you show two fewer units than are actually there. It is a patch rather than a solution, but on platforms you cannot speed up it is sometimes the only measure available.
If no delivery time has been agreed, the statutory period of thirty days applies. In addition, availability information must be accurate: misleading scarcity indications, and withholding or obscuring important information, are unfair commercial practices.
A set of three items draws on three stocks at once, and the availability of the set is that of its scarcest component. If you do not factor that into the calculation, you sell sets you cannot actually make, and you only discover this in the warehouse.
No. Inventory management is about what stock you hold, where it is, and when you reorder. This is about keeping that stock consistent across sales channels. For inventory management itself, we have a page on the inventory management web app.
How often do you cancel an order you were unable to fulfil?
Count the cancellations due to missing stock over the past month and see which channels they came from. If there's a pattern, the problem lies in the delay between your channels. We can build this as a standalone application or as part of a broader custom software project.