A warehouse management system (WMS) is the software that knows where every item sits in a warehouse, and tells each worker or robot what to pick, pack and load next. For the warehouse, it is the system of record: the one database that the company treats as the official count of what is on each shelf.
Every item in a warehouse has a home, called a bin location. A bin location is a code such as C-12-2-4: aisle C, rack 12, level 2, position 4. The WMS records how many units of each product are in each bin. It changes that number every time someone scans goods in or out. The scanning is done on handheld devices that run warehouse mobile apps.
The WMS runs five main jobs. Receiving checks the goods that arrive against the purchase order. Putaway decides which bin each carton goes to. Picking collects the items for each order. Packing puts the items in a box, and the WMS prints the shipping label on a label printer. Dispatch checks that each box is loaded onto the right truck.
Take, for example, a footwear brand's warehouse in Manesar, near Gurugram. At 9 a.m., the order management system sends it 2,400 orders. The WMS does not release them one at a time. It groups them into waves. A wave is a batch of orders that are picked together because they leave on the same truck. The first wave holds 600 orders for the courier's 1 p.m. pickup. For each picker, the WMS builds a pick list in the order of the aisles, so that nobody walks down the same aisle twice. One picker reaches bin C-12-2-4, and her screen asks for three pairs of size 9 sandals. She scans only two, because the bin holds only two. The WMS marks the bin for a stock count, and sends her to a second bin where the same sandals are stored. The order still leaves on the 1 p.m. truck.
The WMS is connected to other systems on both sides. It receives orders from the order management system. It sends each packed shipment to the transportation management system, which books the truck. It reports the stock received and sent to the company's enterprise resource planning (ERP) system, where the accounts are kept. In an automated warehouse, it sends tasks to goods-to-person robots and to an automated storage system instead of to people.
A WMS differs from an order management system. The order management system decides which warehouse fills an order. The WMS decides how the order is filled inside that one warehouse. Many vendors sell both, and many Indian online sellers buy the two together as one subscription. Without a WMS, a warehouse depends on workers who remember where things are. Stock gets lost on the wrong shelf, and orders wait while someone searches for it.