There are five ways to connect your online store to a fulfillment partner: manually, through a plugin or app provided by your fulfillment partner, through your partner’s WMS, through an integration platform, or with a custom integration. For a single online store with a single fulfillment partner, a plugin from your partner is usually sufficient—provided it’s available. As soon as an ERP system, a second sales channel, or returns logic is added, an integration platform offers advantages in terms of management and ease of use. Below, we compare the five approaches side by side, including the costs, lead times, and pitfalls we’ve encountered in practice.
Exactly what needs to go back and forth
Before you choose a route, it helps to understand what a fulfillment integration actually does. It’s never just about “forwarding orders.” In practice, there are five processes running simultaneously:
- Orders from your online store to the warehouse, including payment status, shipping method, and any gift wrapping or inserts.
- Product and item information (SKUs, barcodes, dimensions) so that the warehouse knows what it is receiving and what it needs to pick.
- Transfer inventory from the warehouse back to your online store so you don’t sell what you don’t have in stock.
- Shipping status and Track & Trace information back to the online store and the customer.
- Returns: registration, receipt at the warehouse, and confirmation sent back to the online store with information about inventory and any refunds to the customer.
Each route listed below covers the first stage. The difference lies in how well they handle the other four stages, and what happens if something goes wrong.
The Five Routes
1. Manual: Exporting and Importing
You export orders from your online store (into an Excel or CSV file) and upload them to your fulfillment partner’s portal; you update inventory and shipping statuses yourself. Cost: zero, except for time. Turnaround time: today. Suitable as long as you stay below ten to twenty orders per day and have a single sales channel. The pitfall isn’t the time, but the errors: a forgotten upload means customers waiting, and outdated inventory means potentially selling more than is available.
2. Your fulfillment partner’s plugin or app
Most fulfillment providers offer their own plugin or app for popular e-commerce platforms such as Shopify, WooCommerce, and Lightspeed. Installation and configuration take an afternoon; the partner manages the integration, and orders, inventory, and tracking are handled automatically. This is the logical choice for a single online store with a single fulfillment partner. The limitations become apparent when you also want to connect an ERP or accounting system, add a marketplace, or need returns logic that the plugin or app doesn’t support: this results in two or three separate integrations that aren’t compatible with each other.
3. Through your fulfillment partner’s WMS
If your partner uses its own WMS (warehouse management system), that WMS usually has its own connectors to online stores and marketplaces. In that case, you’re not connecting with “the partner” but with its warehouse system. Advantage: multiple channels at once, mature software. Disadvantage: You’re limited to what the WMS supports, and as soon as you switch fulfillment partners, you’ll need to switch the integration. Inventory and orders run smoothly; integrating with your own ERP or accounting system is often a separate project.
4. An integration platform (iPaaS)
An integration platform like KoneX acts as an intermediary between all your systems: online store, marketplaces, ERP, fulfilment, and carrier. Each data flow from the list above is set up once and works for all channels simultaneously; if you switch fulfilment partners, you replace just one link instead of three. Turnaround time: a few days to a few weeks, depending on how many systems are involved. Cost: a monthly fee per integration or per system. This is the approach to take whenever more than two systems are involved. For a single online store with one 3PL and no ERP, this is more than you need.
5. Custom integration
A developer builds the integration using, for example, APIs from your online store and your fulfillment partner. You get maximum freedom and no subscription, but you do own the entire solution. Any API changes made to your online store platform—such as Shopify—or your 3PL are your responsibility; you’ll need to handle maintenance, error handling, logging, and monitoring yourself. This makes sense if you have specialized logic that no platform supports and a developer who’s committed to staying on board.
Comparison at a glance
| Route | Suitable for | Lead Time | Costs | Management is the responsibility of | Biggest pitfall |
|---|---|---|---|---|---|
| Manual | Up to 10 to 20 orders per day, one channel | Immediately | Time | You | Forgotten uploads, overselling |
| Plugin from your 3PL | One online store, one fulfillment partner | An afternoon | Often included | Fulfillment Partner | The second system does not fit |
| WMS Connector | Multiple sales channels, one 3PL | Days | Through the 3PL | 3PL / WMS Provider | Integrated with the WMS; ERP is separate |
| Integration platform | Three or more systems, multiple channels, ERP | Days to weeks | Monthly fee per connection or system | Platform | Too heavy for a single simple coupling |
| Custom Coupling | Unique logic, in-house developer | Soaking | Hours + Maintenance | You | Maintenance with every API change |
Where Things Usually Go Wrong
No matter which route you choose, we see four mistakes that keep cropping up among our customers:
- Inventory is tracked at two locations. If both your online store and your warehouse are considered “the truth,” you’ll end up with overselling. Choose one source (usually the warehouse or your ERP) and have everything track back to that source.
- Statuses that don’t come back. Orders do go to the warehouse, but the “shipped” status and the tracking number don’t show up. Customers call, and your service desk looks into it.
- Returns outside the coupling. Returns are received at the warehouse, but inventory and refunds are processed manually. This is exactly the process where mistakes are most likely to occur.
- Inadequate error handling. A timeout or a duplicate order number isn’t reported. You’ll find out when a customer asks where their order is.
How does KoneX do it?
KoneX is an integration platform (Route 4). Online stores, marketplaces, ERP systems, and fulfillment partners are connected to the platform; orders, products, inventory, shipping status, and returns flow as separate, trackable streams. Fulfilment partners with a standard integration include PostNL Fulfilment and Paxon Fulfilment (formerly Active Ants); shipping decisions across multiple carriers are automated through partners such as DeliveryMatch. The KoneX Now entry-level plan starts at €24.95 per month for up to two standard integrations; more than 350 customers use the platform. And let’s be honest: if you have one Shopify store, one fulfillment partner, and no ERP, your partner’s plugin is cheaper and faster. That’s exactly what we tell anyone who asks us. KoneX becomes a good option when you have a third system, a second sales channel, or when you want to be able to switch fulfilment partners without having to rebuild everything from scratch. See how Cabau Lifestyle integrated Shopify, Exact Online, and PostNL Fulfilment.
Frequently Asked Questions About Integrating a Fulfillment Partner
Schedule a no-obligation consultation here to discuss which approach to integrating your fulfillment partner is best suited to your situation.
