Real-Time Inventory Synchronisation for E-commerce

Selling through multiple channels is great for revenue but creates a significant inventory challenge. When the same products are listed on your own webshop, Amazon, Bol.com, and a physical store, each sale on any channel must instantly update the available stock everywhere else. A delay of even a few minutes can lead to overselling, where two customers buy the last unit simultaneously on different platforms. Overselling triggers cancellations, negative reviews, and marketplace penalties. An inventory synchronisation layer acts as a single source of truth that distributes stock updates to all connected channels in near real time. Beyond preventing overselling, accurate stock data improves the customer experience: nobody likes adding a product to their cart only to discover it is out of stock at checkout.

How does it work?

The synchronisation engine maintains a central inventory ledger that records the true available quantity for every SKU. Each sales channel is connected through a dedicated adapter: your webshop writes to the ledger via internal API calls, while marketplace channels (Amazon, Bol.com, eBay) are updated through their respective seller APIs. When a sale, return, or manual stock adjustment occurs on any channel, the ledger is updated first, and delta events are pushed to all other channels. The push mechanism uses a combination of webhooks (for channels that support them) and polling (for those that do not), with exponential backoff to handle rate limits gracefully. A reservation mechanism prevents race conditions during high-traffic moments: when a customer adds an item to their cart, a soft reservation is placed on one unit for a configurable hold period. If the purchase is not completed within that window, the reservation expires and the unit is released. For businesses with multiple warehouses, the engine can allocate stock per channel per warehouse, enabling fulfilment routing rules that ship from the nearest location. A reconciliation job runs daily to detect and resolve any discrepancies between the central ledger and channel-reported quantities, logging corrections for audit purposes.

Capabilities

Integration options

Implementation steps

1. 1

   Channel Audit

   Catalogue all sales channels, their API capabilities, rate limits, and current stock management processes.

2. 2

   Central Ledger Design

   Architect the central inventory database with SKU-level quantities, warehouse allocation, and reservation support.

3. 3

   Adapter Development

   Build or configure adapters for each sales channel, implementing webhook listeners, polling jobs, and push mechanisms.

4. 4

   Reservation Logic

   Implement the cart reservation system with configurable hold periods and automatic expiration to prevent phantom stock locks.

5. 5

   Reconciliation Engine

   Develop the daily reconciliation job that compares central ledger values against channel-reported quantities and corrects drift.

User experience

Customers on every channel see accurate stock availability. The admin dashboard provides a single view of inventory across all channels, with alerts for low stock and reconciliation exceptions. Channel-specific stock allocation can be adjusted through an intuitive drag-and-drop interface.

Technical stack

Security

Marketplace API credentials are stored encrypted. Stock update endpoints require authenticated requests. The reconciliation audit log is immutable and accessible only to administrators.

Maintenance

Marketplace APIs change frequently. Adapter updates and rate-limit adjustments are needed a few times per year. Budget approximately 50 hours per year for channel maintenance and reconciliation tuning.