Marketplace Integration: Off-the-Shelf Software or Custom Build? 2026 Guide
How do you keep stock, prices and orders in sync between your own store and marketplaces like Amazon, Trendyol and Hepsiburada? Off-the-shelf vs custom, 2026 price ranges and a checklist.
Every business selling on more than one marketplace hits the same wall sooner or later: the last unit sold on one marketplace still shows as in stock on your website, a price change gets forgotten on another channel, and orders are collected one by one from three different dashboards. Marketplace integration exists to fix exactly this mess. Set up properly, it lets you manage products from one place, reduces stock across every channel at the same time and shows all orders on a single screen.
The catch is that there are dozens of ready-made integration tools on the market, and just as many software firms promising to "build it around you". Prices range from a few thousand Turkish lira a month to projects worth hundreds of thousands. In this article we explain, in plain language, how these systems work, how an off-the-shelf package differs from a custom API integration, and which questions to ask before you decide.
We have deliberately chosen examples from variant-heavy sectors such as furniture, because that is usually where integration really gets tested.
What is marketplace integration and what does it solve?
Marketplaces provide APIs (application programming interfaces) so sellers can connect their own systems. Integration software talks to these APIs: it sends products, updates stock and prices, pulls in new orders and passes shipping tracking numbers back.
Without integration, all of this is done by hand. That is manageable with a few products, but as products and channels multiply, so does the risk of mistakes. Typical problems with manual management include:
- The same item selling on two channels at once, leading to orders for products you no longer have (on marketplaces this means cancellations and a hit to your seller performance score).
- Prices updated on one channel during a promotion and forgotten on another.
- Orders gathered from separate dashboards, with invoices and shipping labels prepared one at a time.
- Every correction to a product description or image having to be entered on each channel separately.
How do stock, price and order synchronisation work?
A good integration is built on the idea of a "single source of truth". The master record for stock and prices lives in one place: your e-commerce site, your ERP or the integration panel itself. Every other channel is fed from that source.
E-commerce stock synchronisation
When an order comes in on any channel, the system deducts it from master stock and sends the new quantity to the other channels. Two methods are used: scheduled jobs that check at set intervals, or notifications triggered the moment something happens (webhooks). Because marketplace APIs have request limits, "real time" in practice usually means a delay of a few minutes. For fast-moving products, setting a safety stock buffer against that delay is a sensible move.
Price synchronisation
Each channel has its own commission and shipping model, so selling the same product at the same price everywhere often makes little sense. Integrations usually apply channel-based rules on top of a master price: for example, a percentage mark-up on one marketplace and a fixed amount added on another. How flexible this rules engine is turns out to be one of the biggest differences between off-the-shelf tools.
Order flow
A marketplace order lands in the integration panel and moves on to invoicing and shipping. The tracking number is reported back to the marketplace so the customer can see delivery updates. Returns and cancellations need to travel back along the same path, and the returns flow is where many businesses struggle most after go-live.
Off-the-shelf marketplace integration software vs custom API integration
Off-the-shelf tools (SaaS) are subscription platforms that bring Amazon, Trendyol, Hepsiburada and other channels together in one panel. They are quick to set up, and maintenance and API updates are the provider's responsibility. In return, you have to fit into the template the system offers.
A custom API integration is written around the way your business works. It fits your existing ERP, warehouse structure and pricing logic. The initial investment is higher, and it needs maintenance whenever marketplaces change their APIs. We cover a broader version of this comparison in our website builder vs WordPress vs custom article; the logic is similar.
| Criterion | Off-the-shelf software (SaaS) | Custom API integration |
|---|---|---|
| Setup time | Within days | Weeks to a few months |
| Cost model | Monthly/annual subscription, possibly per-channel or per-order fees | Project fee + maintenance contract |
| Variant flexibility | Limited to the platform's template | Designed around your own product structure |
| ERP / inventory software connection | Only with supported systems | Can connect directly to your existing system |
| API updates | Handled by the provider | Your responsibility or your development team's |
| Data ownership | Depends on the contract; check export options | Entirely yours |
Marketplace integration cost: indicative ranges for 2026
There is no single answer on price, because cost is driven by the number of channels, monthly order volume, product and variant counts, and extra connections (e-invoicing, shipping, ERP). The ranges below are what we see in the Turkish market and are only meant to give you a rough idea.
- Off-the-shelf software: Entry plans typically start at a few thousand TL per month; multichannel, high-volume packages with add-on modules can reach tens of thousands of TL per month. Some providers charge per-order fees or a setup fee on top.
- Custom add-ons to off-the-shelf software: Connectors built to fill a gap in the panel (for example, a bridge to a bespoke inventory system) are often quoted in the tens of thousands of TL.
- Custom API integration: Projects starting with a single channel and a simple product structure can be in the region of a few hundred thousand TL; projects involving multiple channels, ERP, multiple warehouses and complex variants cost noticeably more. Monthly or annual maintenance comes on top.
A simple way to compare: take three years of total subscription for the off-the-shelf tool and set it against the custom project fee plus three years of maintenance. Then add, on both sides, the staff cost of "the work we will still be doing by hand". That last line is often what decides it.
Products with variants: where does integration struggle in furniture?
For a T-shirt, variants are usually size and colour. For a corner sofa, fabric colour, fabric type, left/right orientation, dimensions and sometimes leg style all combine. These combinations multiply quickly, and every marketplace defines variants differently. One channel may require "colour" and "size" as mandatory attributes, while another asks for different fields depending on the category.
Common situations in furniture include:
- Sets vs single items: When you sell a dining set, the table and chairs are stock-tracked separately. If one component runs out, the set must go out of stock too. Most off-the-shelf tools handle this "bundle" logic only to a limited extent.
- Made to order: Some models are produced per order rather than held in stock. Instead of a fixed stock figure, you need to send the marketplace a lead time.
- Volumetric weight and shipping: Bulky items often travel with contracted freight or delivery with assembly; a standard courier integration is not always enough.
- Channel-specific images: Matching a separate image set to every fabric colour creates a heavy workload as the catalogue grows.
Working with furniture manufacturers in İnegöl and Bursa, Türkiye's main furniture hubs, the most common picture we see is a product structure forced into an off-the-shelf template. The result is that either some variants never get listed on the marketplace, or each one is entered as a separate product and management becomes messy. We go into these sector-specific details on our furniture industry solutions page.
E-invoicing, shipping and ERP connections
E-invoicing
Invoicing rules differ by country. In Türkiye, invoices for marketplace orders are issued through an authorised e-invoice provider (integrator), and most off-the-shelf tools connect to the well-known ones: the invoice is generated automatically and its details are passed to the marketplace. The point to check is whether your own provider is supported. For invoice types, e-archive obligations and thresholds, talk to your accountant and confirm current regulations with the official tax authority; in Türkiye that is the Revenue Administration (GİB). These rules change from time to time, and if you sell in other countries, check the requirements in each market.
Shipping
Most marketplaces offer their own contracted shipping options, while for orders on your own site you may have a separate carrier agreement. A good integration creates the label in both cases and reports the tracking number to the right channel. If you offer delivery with assembly or run your own vehicle fleet, this flow usually calls for a custom solution.
ERP and inventory software
This is usually the real decision point. If you keep stock in an ERP such as Logo, Mikro or Netsis (widely used in Türkiye), another ERP, or a system you built yourself, the integration has to talk to that source. Off-the-shelf tools may offer ready-made connectors for popular ERPs, but with customised installations the data fields may not match. If you want the basics of stock management, our inventory management software guide is a good place to start.
The key question in integration is not "which channels does it connect to?" but "where will the master record for stock and prices live?" Any setup done without answering this will end up being revisited.
Checklist for choosing a marketplace integration provider
When collecting quotes, ask every provider the same questions. Once you put the answers side by side, the differences become clear.
- Which channels are supported? Are the channels you plan to open later (including international marketplaces) on the list, not just the ones you use today?
- Can your variant structure be transferred exactly? Ask for a live test with your most complex product.
- How often does synchronisation run? How many minutes between stock updates, and what happens on busy promotion days?
- Are your e-invoice provider and carriers supported?
- Can it connect to your ERP or inventory software? Is it a ready-made connector or extra development?
- How flexible are the pricing rules? Can you set channel-based percentages, fixed amounts and category-based rules?
- What is the total cost? Get setup, subscription, per-order fees, add-on modules and the annual increase rate in writing.
- Can your data be exported? If you leave, can you take your product and order history with you?
- How does support work? When the order flow stops, who do you contact, through which channel and how fast?
- References: Can you speak to a client in your sector with a similar product structure?
Before choosing an integration, review your own store's platform too. Some platforms include marketplace connections built in, while others depend on an external service. We look at these differences in our e-commerce platform comparison.
When does custom software make more sense?
Off-the-shelf tools are a good starting point for most businesses and should not be dismissed. Still, if several of the points below apply to you, give custom integration serious consideration:
- Your products have multi-dimensional variants, set/bundle structures or made-to-order logic.
- You keep stock in a non-standard ERP or across several warehouses, and no ready-made connector exists.
- Your channel pricing relies on complex rules that change with cost, exchange rates and promotions.
- As order volume grows, per-order fees have started to exceed what a custom system would cost to maintain.
- You want to combine marketplace integration with other internal software, such as a dealer portal, quoting system or CRM, in the same database.
- Your team still spends hours a day in Excel covering the gaps in your off-the-shelf tool.
On the other hand, if you work with a few hundred products, a single variant dimension and standard accounting software, and sell on two or three channels, off-the-shelf software will be both faster and more economical. For those in between, there is a hybrid route: use the off-the-shelf tool as the backbone and custom-build only the missing link (for example, the ERP bridge).
At Fietto Creative, our custom business software and e-commerce website projects always start with the same question: where does the master record for stock, prices and orders live, and which tasks are still done by hand? Write the answers to those two questions on a sheet of paper and you will already have half answered the off-the-shelf vs custom question.
Frequently asked questions
Do I need accounting software for marketplace integration?
No, it is not mandatory. But if you want invoices and stock records in one place, connecting your integration to accounting or ERP software saves a great deal of time. At low order volumes, issuing invoices directly from the integration panel can also work.
Can Trendyol integration be done for free?
Some e-commerce platforms include a basic Trendyol connection in their plans, so you may not see a separate charge. However, needs such as variant mapping, multiple warehouses or an ERP connection usually require a paid package or custom development. The same pattern applies to most other marketplaces.
How quickly do stock changes reach the marketplaces?
It depends on the method used and on each marketplace's API limits. Many systems update every few minutes; near-instant updates require webhooks or frequently triggered jobs.
Is it hard to move from off-the-shelf integration software to a custom system?
If your product and order data can be exported, the switch can be done in a planned way. The most important points are keeping your product mapping codes intact and monitoring stock manually for a short period during the transition.
