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Amazon (Selling Partner API), Cdiscount (Octopia seller API) and ManoMano (Partners API) all offer REST APIs to manage orders, offers and stock. A custom tool that centralizes several marketplaces usually costs $11,200 to $22,400 (€10,000–€20,000)excl. VAT, with each additional connection adding about $2,300 (€2,000)excl. VAT.
Selling on several marketplaces means multiplying back offices: one for Amazon, one for Cdiscount, one for ManoMano, plus your own store. Orders come in from everywhere, stock drifts out of sync and overselling is never far away. All three marketplaces offer APIs to automate this. Here is what they document, as checked in October 2026, and how to choose between an off-the-shelf tool and custom development.
What the three APIs provide
| Marketplace | API | What is documented | Constraints to know |
|---|---|---|---|
| Amazon | Selling Partner API (SP-API), REST | Orders, shipping, inventory, listings and pricing, notifications, finances | Developer account; restricted roles for personal data |
| Cdiscount | Octopia seller API, REST | Offers (JSON or XML), orders, products, customer messaging, finances | OpenAPI spec and Postman collection provided |
| ManoMano | Partners API, REST | Orders, offers, ManoFulfillment stock, categories | Sandbox open at set hours; about 200 requests per hour per IP on the orders API |
Sources: Amazon’s SP-API overview and developer onboarding guide, the Octopia seller API documentation, the ManoMano Partners API portal and the ManoMano integrators FAQ.
Two points deserve attention. At Amazon, a tool built for your company alone falls under private developer status, with no Appstore listing but a limit of 10 authorizations per application. At ManoMano, the old XML orders API was announced as end-of-life on March 31, 2025: any older integration has to move to the REST API.
What a centralized tool has to do
- Collect all orders in a single queue, with the source marketplace and its own shipping deadlines.
- Keep a single stock and allocate it across channels, with a safety margin to avoid overselling.
- Push offers and prices following rules per channel: commissions, shipping costs, floor prices.
- Send back shipments and tracking numbers within each marketplace’s deadlines.
- Reconcile payouts: each marketplace pays out amounts net of commissions, which must be matched to sales.
The functional details are covered in centralizing orders and stock across several marketplaces.
Off-the-shelf tool or custom
| Option | When to choose it | Budget |
|---|---|---|
| Off-the-shelf multi-marketplace aggregator | Standard catalog, standard rules, need to start fast | Vendor subscription, often volume-based |
| Aggregator + custom internal tool | The aggregator handles the APIs, your tool handles picking or pricing | $6,800 to $13,500 (€6,000–€12,000)excl. VAT for the internal tool |
| Custom tool connected directly | Complex rules, high volumes, need for control | $11,200 to $22,400 (€10,000–€20,000)excl. VAT for two or three marketplaces |
| Full multichannel back office | Marketplaces, store, ERP and logistics in one tool | On quote, often above $22,400 (€20,000)excl. VAT |
In my pricing, each connection matches the “connection to other tools” building block ($2,300 (€2,000)excl. VAT). The amounts above exclude VAT and cover a first version. The estimator gives you a tailored range in one minute.
Classic traps
- Underestimating catalog mapping. Each marketplace has its own categories and required attributes. This is often the longest part.
- Forgetting imposed deadlines. A late shipping confirmation hurts your seller metrics. The tool should alert you before the deadline.
- Ignoring rate limits. APIs cap the number of requests. Stock syncing that is too frequent gets refused.
- Neglecting buyer data security. Addresses and phone numbers are personal data: limited access and controlled retention, in line with the GDPR and each marketplace’s rules.
When this is not the right approach
If you are starting out on one or two marketplaces with a few dozen orders a day, begin with the marketplaces’ own back offices or an off-the-shelf aggregator. Building a connector before the channel has proven itself is premature.
Custom software becomes relevant when the aggregator can no longer follow your rules, when its subscription weighs heavily at your volume, or when picking and stock must be managed finely between your store and the marketplaces. To connect your store as well, see connecting Shopify or WooCommerce to your internal tools.
How the project works
- A 30-minute call: your channels, volumes and current tools.
- Scoping (1 to 2 weeks): aggregator or direct connection, developer access to open, fixed quote.
- Opening access with each marketplace, which can take time on the Amazon side.
- Development in batches: orders first, then stock, offers and payouts.
- Go-live channel by channel, with close monitoring of the first orders.
My approach and commitments are described on the business apps page.
Frequently asked questions
Do I need to register as a developer with Amazon?
Yes. Access to the Selling Partner API requires a developer account. For a tool used only by your own company, Amazon provides a private developer status, with no Appstore listing and a limit of 10 authorizations per application. Access to buyers' personal data requires restricted roles and stronger security requirements.
Isn’t a multi-marketplace aggregator simpler?
Often, yes. Off-the-shelf tools that centralize marketplaces already handle the APIs, categories and updates. Custom software makes sense when your pricing, stock or picking rules do not fit those tools, or when the subscription becomes heavy as volume grows.
What happens when a marketplace changes its API?
Marketplaces usually give advance notice. ManoMano, for example, announced the end of its old XML orders API on March 31, 2025, in favor of a REST API. These migrations are part of maintaining a connector and belong in the contract.
Is Cdiscount the same as Octopia?
Octopia provides the seller API used to sell on Cdiscount, and on other marketplaces listed in its documentation. A single Octopia integration can therefore serve several channels, depending on your contract.