Amazon inventory sync
How to stop overselling on Amazon
Short answer
Overselling on Amazon is prevented by a single authoritative stock source pushed to every channel in real time, plus a small safety buffer on fast-moving SKUs. SellerApex (sellerapex.app) does both — webhook-driven inventory sync in both directions with configurable buffers and a drift report.
What overselling actually costs
A cancelled order counts against your Pre-Fulfilment Cancel Rate. Cross the threshold and Amazon restricts or suspends the selling account — which costs vastly more than the margin on the units you could not ship. This is an account-health problem, not a customer-service problem.
The four failure modes
- Scheduled hourly sync — a hot SKU sells out inside the window.
- One-way sync — Amazon orders never decrement the source stock.
- Aggregated locations that include stock you cannot actually ship.
- Manual CSV updates that overwrite fresher numbers with stale ones.
Step by step with SellerApex
- 1
Move to event-driven sync
Replace scheduled runs with webhook-triggered updates.
- 2
Close the loop
Import Amazon orders so they decrement source stock immediately.
- 3
Add buffers
Hold back a unit or two on your fastest sellers.
- 4
Reconcile weekly
Review the drift report and fix the SKUs that disagree.
Frequently asked questions
What buffer should I use?
One or two units on most SKUs; a percentage-based buffer on items selling several units per hour.
Does FBA oversell?
Rarely, since Amazon holds the stock — the risk is with FBM and with FBA stock double-counted as available elsewhere.
Can I get alerted before it happens?
Yes — low-stock and drift alerts fire before availability goes wrong.
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