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How to avoid overselling on Shopify and Mercado Libre

Why you end up selling products you no longer have when you sell on Shopify and Mercado Libre, and seven practices to prevent it.

3 min read

In short

Overselling happens when the same product sells on two channels and the stock on one of them isn't updated in time. You prevent it with a single source of truth for your inventory, unique SKUs that link each listing to its product, safety stock for your best-selling products and an automatic sync that keeps Mercado Libre Full stock separate.

Selling on Shopify and Mercado Libre at the same time multiplies your opportunities, but it also opens a door: selling an item you no longer have. That's called overselling, and it almost always ends in a cancellation.

This guide explains why it happens and what you can do to prevent it.

What overselling is

Overselling happens when a customer buys a product that already sold on another channel. For example: you have one unit left, it sells in your Shopify store and, before you update Mercado Libre, someone buys it there too.

The result is a sale you can't fulfill. You have to cancel it, and on Mercado Libre, sales canceled by the seller hurt your reputation.

Why it happens

  • You update stock by hand. There's always a gap between a sale and the next update, and in sales seasons like Buen Fin that gap fills up fast.
  • The same product is in several listings. If you have a Clásica and a Premium listing for the same product and only update one, the other keeps selling.
  • Your SKUs don't match. If the Shopify product and the Mercado Libre listing don't share a code, no tool can tell they're the same thing.
  • You mix Full stock with your own. The inventory in Mercado Libre's warehouses isn't the same as the inventory in your warehouse, and counting them together throws both off.
  • You count locations that don't fulfill your sales. If your physical store sells over the counter, its stock can disappear in minutes.

Seven practices to avoid overselling

  1. Choose a single source of truth. Decide where your inventory lives, for example in Shopify, and have the other channels copy it. That way you only update it in one place.
  2. Give each variant a unique SKU. Use the same SKU in Shopify and on Mercado Libre. It's the most reliable way to link each listing to its product.
  3. Use safety stock. Keep one or two units of your best-selling products off Mercado Libre. If two customers buy at the same time, those units absorb the difference.
  4. Count only the locations that fulfill. If your Mercado Libre sales ship from a warehouse, list that warehouse's stock and not your physical store's.
  5. Keep Full stock separate. What's in Full is managed by Mercado Libre. Your sync should update only your own stock and never overwrite Full stock.
  6. Automate the sync. A tool that updates stock as soon as it changes in Shopify closes the gap between a sale and the update.
  7. Review sync errors. An unlinked listing or a rejected stock update is an oversell waiting to happen. Review them every week.

How Toldo solves it

Toldo is a Shopify app that syncs your Mercado Libre account and is rolling out with a group of founding partners. It takes Shopify stock as the source of truth, links your listings by SKU or barcode and never guesses when there's a conflict. It lets you choose the locations that count and set safety stock and a maximum, and it never changes Full stock.

If you want the details, read Stock rules and Link listings.

Frequently asked questions

What is overselling on Mercado Libre?

It's a sale of a product you no longer have in stock, usually because it sold on another channel before your listing was updated. It ends in a cancellation.

What is safety stock?

Safety stock means the units you don't list on a channel, so you have some margin if two customers buy the last piece at the same time. It's also called a buffer.

How often should I update my stock?

Ideally, it updates as soon as it changes. If you do it by hand, do it after every sale and, at a minimum, every day.

Does Full stock sync with Shopify?

Full stock is managed by Mercado Libre and only changes when you send merchandise or make a sale. A good sync reads it to show it to you, but never overwrites it.