Stock numbers that match reality:
across every channel and every warehouse you run
The most common inventory failure is not a missing feature, it is a single number that is wrong: a stock count that does not match what is actually on the shelf because it was never updated consistently across every channel selling it.
What it is
An inventory and warehouse management system keeps one real number for how much stock exists and where, synced across every channel that sells it, so a sale on one channel immediately reduces what shows as available everywhere else. Without this, the common failure is overselling, two channels both show a product in stock when only one unit actually exists, which turns into a canceled order and an unhappy customer after the fact instead of an accurate “out of stock” before the sale.
We rebuilt a factory ERP from a lost cloud account into a self-hosted system handling over twelve thousand records, and supported a supplements brand’s growth that included opening a second warehouse in a new country, both cases where accurate, synced stock data was the foundation everything else depended on.
When you need it (and when you do not)
You need this once you sell across more than one channel, your own store plus a marketplace, or more than one location, and stock counts have started drifting out of sync enough to cause real problems: oversells, stockouts nobody saw coming, or a reorder decision made on a number that turned out to be wrong. Multi-warehouse operations need this structurally, since manual reconciliation across locations does not scale past a very small operation.
You do not need a dedicated system if you sell through a single channel from a single location and your platform’s built-in stock tracking is accurate; adding a separate inventory system in that case would just be a second source of truth to keep in sync with the first, which defeats the purpose.
How we build it (stack, components, integrations)
Stock lives in one PostgreSQL table per SKU per location, with every sale, return, or adjustment recorded as a movement rather than just overwriting a number, so the full history is auditable and a discrepancy can actually be traced to its cause. Sales on any connected channel, your store, a marketplace, a point-of-sale system, decrement the same shared count through webhooks or scheduled sync, whichever the channel’s API supports, so availability shown to a shopper reflects reality rather than a stale snapshot.
Reorder alerts trigger on a threshold calculated from actual sell-through rate, not a static number someone picked once and never revisited, and warehouse staff use a simple barcode or SKU scanning interface to record receiving and picking without manual data entry errors. Supplier and purchase order tracking ties incoming stock to the same system, so a reorder’s expected arrival date is visible alongside current stock levels.
What to watch (risks, cost of ownership, vendor lock-in)
Multi-channel sync is only as reliable as its weakest integration; a marketplace API that rate-limits aggressively or an unreliable webhook can introduce drift if there is no reconciliation process checking for and correcting mismatches. Reorder thresholds that are set once and never revisited will eventually be wrong as sales patterns shift seasonally or with growth, so the system needs a periodic review built into someone’s actual workflow, not just a one-time setup.
Seasonal demand swings are worth planning into the reorder logic specifically, since a threshold calculated from a slow month will under-order heading into a fast one. We build reorder points that account for recent trend, not just a flat historical average, so the alert still fires early enough to matter when demand actually shifts.
Price and timeline
| Option | Price | What it covers | Timeline |
|---|---|---|---|
| Single-warehouse sync | from $5,000 | Multi-channel stock sync, reorder alerts | 5 to 7 weeks |
| Multi-warehouse system | from $10,000 | Several locations, movement history, scanning | 7 to 10 weeks |
| Full system with supplier tracking | from $16,000 | Purchase orders, supplier integration, full reporting | 10 to 12 weeks |
Running cost is usually $30 to $80 a month in hosting, depending on sync frequency and channel count.
Related
This pairs with order management system since order fulfillment and stock levels are directly connected, and with marketplace integrations for sellers whose stock needs to sync to external platforms too. See the e-commerce service page for package details. For real inventory and operational systems we have built, see the supplements store Balkans sales ×10 case study and the factory ERP recovery case study.
Had an oversell because two channels disagreed on your stock count? Get in touch and we will look at your current sync setup first.
FAQ
How much does an inventory system cost?
From $5,000 for single-warehouse, multi-channel stock sync. $10,000 to $18,000 is typical for multi-warehouse tracking with reorder automation and supplier integration.
How long does it take?
5 to 12 weeks depending on how many warehouses, channels, and existing systems need to sync into one source of truth.
What is the stack?
PostgreSQL as the single source of truth for stock levels with row-level locking on sale events, FastAPI for the sync logic across channels (Shopify, WooCommerce, marketplaces), and a simple scanning interface for warehouse staff using barcode or SKU lookup.
Who owns the inventory data?
You. Stock levels, movement history, and supplier records live in your own database, which also means your reporting is not limited to what a third-party inventory app chooses to show you.
Who maintains it after launch?
The sync logic runs unattended once connected to your channels. Supplier and reorder rules need periodic review by your team through the admin panel.