Order Management System (OMS)
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An OMS decides which stock is promised to which order, and from where it ships. What it does, where it ends and a WMS begins, and when you actually need one.
An Order Management System takes orders from every channel you sell through, decides how each one will be fulfilled, and hands the work to whoever is doing the fulfilling. It holds the single view of what has been sold, what has been promised, and what is still available to promise.
A WMS runs a building. An OMS runs the decision above the building — and if you have one warehouse and one channel, you do not need one. The moment you have two of either, you do.
What this subject holds
Two channels want the last piece. Which system decides, and how long before the other one knows?
How much stock do you hold that you cannot promise?
Which system owns the stock number your channels read?
What an OMS actually decides
Four decisions, and they are the reason the category exists.
What can we promise
Who gets it when there is not enough
Where it ships from
What happens when it comes back
OMS vs WMS vs ERP
| ERP | OMS | WMS | |
|---|---|---|---|
| Answers | What did the business do, and what does it owe | What do we promise, and from where | How the work gets done in the building |
| Holds | Finance, purchasing, master data | Orders, allocation, availability across sites | Locations, tasks, stock movements |
| Scope | Whole company | Every channel and every site | One building |
| You need one if | Always | More than one channel or more than one site | You run a warehouse of any complexity |
The common confusion is with the ERP, because most ERPs have an order module. It records orders and it invoices them. It does not decide allocation across channels, it does not route fulfilment across sites, and it does not hold a real available-to-promise position. That is the gap people discover after the second warehouse opens.
Where the boundary sits
When you need one, and when you do not
You do not need an OMS if you have one warehouse and one sales channel. The allocation question has one answer and a WMS handles it.
You probably do if any of these is true:
- You sell through more than one channel and they compete for the same stock.
- You hold stock in more than one place, including at a 3PL.
- You have oversold on a marketplace because two systems each believed they owned the unit.
- Somebody reconciles availability between systems by hand.
- Which customer gets scarce stock is decided by whoever asks most persistently.
The honest test: if two people in your business could give a customer a different answer to “can you ship this today”, the allocation decision is not being made anywhere. That is what an OMS is for.
Where we sit
BizBloqs provides the OMS and the WMS as one platform, so the allocation decision and the work it produces sit in the same system and share one stock position. No reconciliation between a decision layer and an execution layer, because there is no boundary to reconcile across.
Where you already run a WMS you are happy with, the OMS can sit above it. Where you run an ERP, the OMS complements it rather than replacing it — the ERP keeps the financial record and we keep the promise.
The longer argument
Our paper Sell less than you have works through the allocation problem properly — why most operations optimise the wrong number, what a broken promise actually costs on a channel that rates you, and why the right amount of stock to offer is usually less than you have.
Questions worth asking a vendor
- Show me available-to-promise for one SKU across every warehouse and channel, as three separate numbers: committed, reserved, free.
- What is the measured latency between a pick confirmation and each sales channel's availability updating? Not the design target — the measured number.
- How do I reserve stock for one customer or channel without hiding it from the others entirely?
- Can I set a per-channel threshold below which that channel stops being offered stock, regardless of physical availability?
- Is fulfilment routing a cost decision on this order, or does it account for the opportunity cost of depleting that location?
- How do I measure fulfilled-against-promised, separately from fulfilled-against-received?
- After this is installed, how many systems hold a stock quantity for the same item? Name them.
Question two is the one most vendors answer badly, and it is the number that decides whether you oversell.
Common questions
What is an order management system?
Software that takes orders from every channel, decides how each will be fulfilled and from where, and holds the single view of what is available to promise across the whole business.
What is the difference between an OMS and a WMS?
An OMS decides what is promised and which site fulfils it. A WMS decides how that work gets done inside the building — putaway, picking, packing, despatch. One runs the decision, the other runs the operation.
Is an OMS the same as the order module in my ERP?
No. An ERP order module records and invoices orders. It does not allocate scarce stock between competing channels, route fulfilment across sites, or hold a true available-to-promise position across locations.
Do I need an OMS if I only have one warehouse?
Not for the location decision. But if you sell through several channels competing for the same stock, the allocation question still exists and a WMS alone does not answer it.
What is order orchestration?
The coordination of everything between an order being placed and it being fulfilled — allocation, routing, splitting, sourcing and returns — across channels and locations. It is the work an OMS does.
Can an OMS work with an existing WMS?
Yes, and it commonly does. The thing to check is how many systems end up holding a stock quantity for the same item, because every additional copy is a reconciliation task and a number that can be wrong when a customer asks.
Short definitions sit in the glossary entries for OMS and order orchestration. Alongside this page: what an order management system does, EDI integration in order management and OMS versus WMS.
Order management is available at all tiers. Multi-site allocation and fulfilment routing are part of SME+ and Enterprise.
Ready to see BizBloqs on your own process?
Book a demo and we will walk your warehouse and order flow end to end — inbound, storage, picking, shipping, returns — and tell you honestly what BizBloqs would change.
Two questions about your own channels
Two channels want the last unit. Which system decides — and how long before the other channel knows?
What does one cancellation cost you on a marketplace — not in euros, but in where you appear in the results?