Selling it at the price you meant, only when you have it

Two promises on every listing

A product page on a marketplace makes two claims on your behalf. One is the price. The other is availability: we have this and can ship it. Buyers read both as facts. The marketplace reads them as commitments and keeps score.

Most of the trouble for a manufacturer or distributor selling through marketplaces — for example Amazon Seller Central and Vendor Central, eBay, Walmart Marketplace or Etsy — comes from those two numbers drifting away from the truth in the ERP. Nobody decides to let them drift. It happens because the ERP knows the real price and the real stock, and the listing is updated by something else: a person, a spreadsheet, a connector that runs when it feels like it.

Both directions of wrong cost money

Showing stock you don’t have

This is the one everybody fears. A listing says twelve available, the shelf has none, an order arrives. You cancel it or ship it late. Either way the marketplace notices. Cancellation rate, late shipment rate and valid tracking rate are scored on every major marketplace. Slip past a threshold and listings lose placement, the buy box goes to someone else, or the account is warned, fined or suspended. One oversold item isn’t fatal. A connector that oversells quietly for a month can be.

Hiding stock you do have

The less obvious failure is the reverse. A listing shows zero because the last update didn’t run, or because stock arrived and nothing told the marketplace. No penalty, no warning — the item just doesn’t sell. Inventory you paid for sits on a shelf while a competitor takes the order. For assemblies and kits it is worse: you might have every component to build twenty and show none, because the listing reads finished-goods stock instead of what you can actually make.

The wrong price

Price drift is quieter still. A cost increase gets passed through on your own website and to wholesale customers, and the marketplace listing keeps last year’s price because nobody owns it. Once fees and free shipping come off, a marketplace sale at a stale price can lose money on every unit while looking like healthy volume. The opposite error, priced well above where you meant, simply means no sales and no explanation.

A marketplace doesn’t care why your listing was wrong. It only counts that it was.

Why the ERP should drive it

The ERP already knows the answers. It holds the price level you set for marketplace channels, on-hand and committed stock, and for built items what can actually be produced from components on hand. Any other source of truth is a copy, and copies drift.

So the design principle is simple: the ERP decides, the channels are told. Each marketplace is a destination that receives price and quantity and reports back what it now shows, not a second system someone maintains by hand.

What a sync you can trust looks like

• It finds the listings itself. Nobody maintains a list of which items live on which marketplace. The sync reads each channel’s catalog, matches listings to items, and shows plainly what didn’t match — a listing with no item, an item that’s been discontinued but is still for sale.
• It sends buildable quantity for built items. For kits and assemblies, the number that matters is what you can build today, not what is on the shelf finished.
• It knows what zero means on each channel. Some marketplaces accept a quantity of zero; others refuse it and want the listing deactivated instead, then reactivated when stock returns. The sync has to handle both, or zero never arrives.
• It shows margin before it sends a price. Each price change shows estimated margin after marketplace fees and the real cost to ship that item, so a price that loses money is visible before it goes out.
• It separates “we would send” from “they now show.” A preview calculated from ERP data and a value read back from the marketplace are different things, shown in different places. You never have to wonder whether a number was actually pushed.
• It runs on its own and reports by exception. A schedule pushes changes without anyone clicking, and a short digest twice a day lists what failed or looks wrong, instead of an alert for every hiccup.
• It covers wholesale programs too. Amazon Vendor Central works differently from Seller Central — Amazon buys from you, usually through EDI purchase orders — but the inventory and cost you report there should come from the same ERP numbers as every other channel.
• It is one system for every channel. Marketplaces and your own brand sites get the same price logic and the same quantity, from one console.

Build versus buy

There are good prebuilt connectors, and for some companies they’re the right answer. We built this one inside the ERP for three reasons that will apply to plenty of others: the quantity rule for built items was specific to how the business makes product, the existing connectors had been failing silently or updating only when inventory moved, and the team wanted one place to see every channel’s price, stock and margin side by side. A sync you can see into is a sync people trust, and one they trust is one they leave running.

What it bought

Each channel now gets its price and stock from the same place, on a schedule, with a read-back confirming what the marketplace actually shows. Discontinued items stop being sold by accident, built items show what can really be shipped, and nobody keeps a spreadsheet of listings. The two promises on every page are the ERP’s promises now, which is the only place they can be kept.

Getting there wasn’t clean. Every marketplace has its own ideas about authentication, zero quantities and rate limits, and the console needed several rounds before people found it obvious. Those lessons are in the companion piece.

Related: what four marketplaces taught us about syncing, and pricing as a process, not an event.