Selling on Marketplaces and WhatsApp at Once, Where Does the Stock Count Live?

The same product is sold on Shopee, Tokopedia or TikTok Shop, WhatsApp, and sometimes a physical store. Each channel has its own stock number. The item sells out through WhatsApp, but the marketplace still shows it as available. An order comes in, the seller can't fulfill it, and ends up canceling or asking the buyer to cancel.

This is called overselling, and it costs more than one canceled order.

Why overselling is costly

On marketplaces, cancellations caused by the seller get recorded. Take Shopee. In the Penalty Point System guide from Shopee's Seller Education Hub (in Indonesian):

• The non-fulfillment rate is the percentage of orders in the last 7 days that were canceled or returned because of the seller.
• If that rate is 10% or more and there are 30 or more unfulfilled orders, the seller gets 2 penalty points.
• Asking a buyer to cancel an order through chat is also a violation, worth 2 penalty points.
• Sellers with high penalty points can temporarily lose exclusive benefits.

Rules like these can change, so check the latest version in each marketplace's seller education center. Beyond penalties, there are disappointed customers, bad reviews, and admin time spent apologizing. For WhatsApp buyers, the loss is usually trust.

The principle, one source of truth for stock

The problem isn't the sales channels, it's a stock number kept in many places. The fix: one master stock table. Every sale from any channel reduces the number in that table, and the stock shown on each channel follows the master table, not the other way around.

It sounds simple, but it's what separates stock that's under control from stock that's guessed.

Three levels of fix

Levels 1 and 2 can be built on Google Sheets. Its limits, and when to move on, are in When Google Sheets Is Enough as a Web App Database, and When to Move On. For level 3, weigh the monthly subscription against building your own system, as I discuss in Instead of Stacking CRM and POS Subscriptions, Investing in Your Own Website Can Make More Sense.

Habits that keep stock accurate

Even the best system drifts if the habits don't follow. Here's what I'd suggest:

1. One person or one system holds the master stock. Other channels only read from it.
2. Record everything that leaves, including damaged goods, samples, and items used internally. Stock gaps often come from the "just a few".
3. Check returns first before counting them back as sellable stock.
4. Do regular stock counts, for example weekly for fast movers and monthly for the rest.
5. Use a buffer for best-sellers, because those are the items that oversell most often.
6. Don't ask buyers to cancel. If you have to cancel, do it yourself and fix the cause.

The same problem at a larger warehouse scale, going from paper and WhatsApp chats to an integrated system, is in the warehouse management system case study.

Wrapping up

Selling across many channels is good for sales, as long as the stock is held in one place. Start with one master stock table and the habit of recording everything that leaves. Automation and integration can come later, once the pattern is tidy.

If the stock in your online shops and on WhatsApp is often out of sync, tell me which channels you use first.