Automatic inventory sync
Product details, prices and stock flow from your connected store to Mastersel. Update them in your store; processing times depend on your integration and the marketplace.
- Sync
- Automatic
- Overselling risk
- Reduced
- On SKU count
- No limit
- Stock updates across channels
- Automatic
- Overselling risk
- Reduced
- SKUs handled seamlessly
- 10,000+
- As the master
- Your store
Essential for multi-channel sellers managing stock across platforms
If you sell on more than one marketplace, accurate inventory is the difference between happy customers and account suspensions.
Sellers expanding from one marketplace to many
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
High-volume sellers during peak seasons
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
Sellers wasting hours on manual CSV updates
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
Multi-channel inventory management
Product details, prices and stock flow from your connected store to Mastersel. Update them in your store; processing times depend on your integration and the marketplace.
Automatic stock updates
Product details, prices and stock flow from your connected store to Mastersel. Update them in your store; processing times depend on your integration and the marketplace.
Overselling risk
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
Single source of truth
Your store inventory is the master. All marketplace quantities derive from your actual stock — and orders processed via order management keep everything aligned. No conflicting numbers, no data discrepancies. Whether you update stock through your Shopify admin, WooCommerce dashboard, or via bulk import, every change flows outward to all connected channels automatically.
Automatic updates
No CSV uploads, no manual adjustments, no spreadsheets. Inventory flows automatically between your store and every connected marketplace, with shipping quantities always in sync. The API-based integration replaces the 2-5 hours per week that traditional multi-channel sellers spend on manual stock reconciliation, while also eliminating the human errors that cause ghost listings and overselling.
Inventory accuracy at scale
- Markets with synchronized stock levels
- 30+
- For stock changes to propagate across all channels
- Automatic
- CSV uploads or manual adjustments needed
- 0
- Saved vs traditional inventory tools
- €100-300/mo
Always accurate, always automatic
Connect your store once. Inventory stays in sync across every channel without any manual effort.
Store becomes master
When you connect your store, your inventory becomes the single source of truth. All marketplace quantities are derived from your actual stock.
Sales trigger updates
Product details, prices and stock flow from your connected store to Mastersel. Update them in your store; processing times depend on your integration and the marketplace.
Restocks propagate
When you add new stock in your store, all marketplace listings update automatically. Monitor everything from your dashboard — no need to manually adjust quantities anywhere.
Automatic stock updates
Automatic stock updates
Without Mastersel
- Update each channel separately
- High overselling risk — gaps between updates
- Scattered data across platforms
- CSV uploads, manual edits
- Hours per week on reconciliation
- Inventory management software costs
- Variant-level errors cause wrong stock
- Restocks require manual push to each channel
With Mastersel
- Automatic stock updates
- Automatic inventory sync
- Single source of truth
- Fully automatic
- Zero — runs in the background
- Free — unlimited SKUs
- Variant-level accuracy across all channels
- Restocks auto-propagate everywhere
Inventory sync FAQ
How fast does inventory sync?
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
Can overselling happen?
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
Where does inventory data come from?
Your Shopify or WooCommerce store serves as the master source of truth. When you update stock in your store admin — whether adjusting a single product or bulk-importing new inventory — all marketplace listings update automatically. Mastersel supports variant-level sync for attributes like sizes and colors, and bundle or kit stock is calculated from component inventory. This ensures every channel reflects accurate availability down to the individual variant.
Do I need to upload CSV files?
Updates depend on your integration and marketplace processing. Keep stock current and take extra care with low-stock products; synchronisation reduces, but does not eliminate, overselling risk.
Are there per-SKU fees?
No. Inventory tools like Linnworks charge €100-300/mo, and ChannelAdvisor starts at €500+/mo. Mastersel includes unlimited SKU sync completely free. Even sellers managing 10,000+ SKUs pay nothing for inventory management. There are no per-SKU charges, no sync fees, and no usage limits — track stock levels in analytics and manage inventory at no additional cost.
How does Mastersel inventory sync handle products with multiple variants like size and color combinations?
Mastersel syncs inventory at the individual variant level, not just the parent product level. Each size-color combination — for example, a blue T-shirt in size M — is tracked as its own stock unit across every connected marketplace. When that specific variant sells on one channel, only that variant's quantity decrements everywhere else. This prevents the common problem where selling one variant incorrectly reduces stock for a different variant. Bundle and kit products are also supported, with component-level inventory calculations ensuring that selling a bundle correctly reduces the stock of each included item across all channels.
What happens to my inventory levels on marketplaces if my Shopify or WooCommerce store goes offline temporarily?
Mastersel maintains a cached copy of your latest inventory state, so a brief store outage does not cause marketplace listings to display incorrect stock levels. During the offline period, any marketplace sales are still processed and queued. Once your store reconnects, all pending inventory changes are reconciled automatically — stock decrements from marketplace sales are applied to your store, and any updates you made before going offline are pushed to marketplaces. This ensures data integrity is maintained even during unexpected downtime, without requiring any manual intervention on your part or disrupting your shipping workflow.
Automatic stock updates
Overselling is the single biggest operational risk in multichannel e-commerce. When a product sells on one marketplace but stock levels do not update on other channels, subsequent orders arrive for items that no longer exist. This leads to order cancellations, negative reviews, marketplace penalties, and — in severe cases — account suspensions. For sellers operating across European marketplaces, the window between a sale and a potential oversell can be seconds.
Product details, prices and stock flow from your connected store to Mastersel. Update them in your store; processing times depend on your integration and the marketplace.
How stock discrepancies destroy marketplace performance
European marketplaces track seller metrics closely. Order cancellation rates, shipping delays, and stock accuracy all factor into your seller ranking and search visibility. A single oversell incident can trigger a warning; repeated incidents can reduce your listing visibility or suspend your account entirely. For sellers using manual inventory management (spreadsheets, CSV exports), maintaining accuracy across multiple channels becomes impossible at scale — especially during high-volume periods like Black Friday when orders arrive every few seconds. Automated sync is not a convenience feature; it is an operational necessity for serious cross-border sellers.
Variant-level accuracy across every channel
Inventory sync at the product level is insufficient for sellers with variants. A t-shirt listing might have 20 variants (5 sizes x 4 colors), and each variant has its own stock count. Mastersel syncs at this granular level, ensuring that when a Medium Blue sells out on one marketplace, it is marked as unavailable across all channels — while Large Blue remains available everywhere. This precision prevents the most common type of overselling, where a product appears in stock because other variants exist, but the specific variant ordered is already depleted. Combined with multichannel selling and unified order management, variant-level sync gives you confidence to list your full catalog without fear of stock errors.
Multi-channel inventory sync at no extra cost
No sync fees, no per-SKU charges. Shipping included — completely free.