Mercur

Add eCommerce Marketplace Solution to Your Existing Store

eCommerce marketplace solution opens your catalog to third-party sellers without rebuilding your store. Keep your stack, code, and margins with Mercur.

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Three ways to add an eCommerce marketplace solution to your store

Two of them replace your store. The third way runs next to it.

How it worksBest for
SaaS marketplaceRebuild the whole platform, rent the engine, and give up a share of every sale to the software maintaining it.Businesses with no engineering capacity.
Plugins and custom codePlatform functionalities are plugins or custom code added to the core. Every one of them adds technical debt your team must update after each release.Small catalog, a handful of vendors, and a store you are willing to maintain yourself.
Parallel marketplace layerThe marketplace runs beside your first-party store on your own infrastructure. Predictable costs, no cut of sales, ownership of the platform.Existing store that needs third-party selling without a replatform.

Add a marketplace layer next to your first-party store with Mercur

Mercur is eCommerce marketplace solution that adds marketplace functionalities, while your core commerce engine stays untouched. You add third-party selling on top, on infrastructure you control. No migration and no replatforming.

Zero GMV fees

The license is your only platform cost. Your success isn't taxed.

Own the source

Open source, full source for licensees – an engine you can read, audit, and extend.

Your infrastructure

Any cloud, on-premise, or air-gapped. Data residency is your decision.

80% already inside

You customize the last 20%. Upgrades never overwrite your work.

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Your storefront

StorefrontProductsBrand
CartCheckoutCustomers

Mercur

Third-party vendorsOffers & BuyBoxPayouts

Shared layer

What changes in your store once you add a marketplace?

You bring new vendors to your store – the suppliers and partners you already work with. No network to rent, no marketplace to share.

1

Onboard a vendor

A configurable application, KYC and KYB through your payment provider, and a hard rule: no verification, no payout.

Vendor onboarding, step 1 of 5: the store details form a new vendor fills in before verification
2

List the catalog

Bulk import by file or API with a mapping wizard. Listings dedupe by EAN, so three versions of one phone become one product with competing offers.

A vendor's product record in the panel: description, media, attributes and the variant table
3

Win the sale

Offers compete on price and availability. The BuyBox picks the winner and shows every vendor standing behind it.

A storefront product page: two verified vendors offering the same phone, sorted by lowest total price including delivery, with the winning offer selected
4

Take a mixed cart

One checkout across your own products and third-party offers, with shipping costed per vendor.

One storefront cart split into parcels – two third-party vendors and the store's own – each with its own estimated delivery, under a single checkout
5

Split the order

The cart breaks into a separate order and payment per vendor, on its own.

The admin order list: one group ID expanding into a separate order per vendor, each with its own payment and fulfillment state
6

Fulfill and track

Logistics classes, lead times, lockers, and multi-shipment – with a status flow where only the admin marks an order received.

Creating a fulfillment: stock location, shipping method and the line items going into this shipment
7

Settle and pay out

An append-only ledger, real Pending, Payable, and Paid balances with a Reserved bucket for holds, statements, and invoices. The balance a vendor sees is the money they get.

The settlement ledger for one vendor: Pending, Payable and Paid balances above the ledger movement rows, with statements and payouts alongside
8

Handle returns and disputes

Per-line returns on your policy window, refunds that match the books, and disputes that hold a payout until they close.

The admin dispute list: each dispute carries its seller, order, reason and state, and the one still open holds the vendor payout

Discover how an eCommerce marketplace solution fits your store

Tell us about your eCommerce and what you want to sell third-party. Our experts will show you how it connects to your stack, how long it takes, and what it costs.

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How to choose an eCommerce marketplace solution

The answers decide what the project costs and how much of it you control.

1

Is multi-vendor built in, or added by a plugin?

Some solutions have vendors, offers, and payouts built in. Others add them with a plugin. If that plugin stops being updated, the part that pays your sellers stops working.

2

Do you have to change your platform?

Some solutions require moving your catalog and checkout onto a new platform. That is a full migration, with a huge budget and long development.

3

Do you pay more when sales grow?

Ask for the pricing structure. A license is one price you can put in next year's budget. A percentage of sales is a bill that gets bigger every month the marketplace works.

4

Can you change the code?

Some platforms are closed, so you can configure only what the vendor allows. Others hand you the full source, so your team can customize whatever your business needs.

How Mercur compares with SaaS marketplace platforms

SaaS MarketplaceMercur
Core technologyClosed, vendor-onlyOpen source (MIT), public
Enterprise codeBlack boxFull source for licensees
IntegrationsSeparate productsBuilt into one platform
CustomizationTickets and workaroundsYour own layer, official extension points
DeploymentVendor cloud onlyAny cloud or on-premise
Cost modelA percentage of your GMVZero GMV fees
ExitLock-inYou keep what you paid for
Developer poolCertified specialistsAny web developer

Built to fit the stack you have

Connect is the integration layer built into the platform on the same login and upgrade path.

Two separate pipelines

Product content and offers sync on separate tracks. A price or stock change goes out the moment it happens, independent of catalog imports.

Errors you can act on

Row-level reports show which row failed and why, while the rest of the import finishes.

AI-native product import

A vendor's file rarely matches your catalog format. The AI proposes the mapping and your vendor confirms it.

Connect the systems you already use

Your ERP, PIM, OMS, and storefront platforms connect through one framework.

Connect is part of Mercur Enterprise.
Only the Magento 2 Connector is open-source.

What the integration process looks like

The team that builds Mercur can take you through all four steps.

1

Discovery

Map your stack, your 1P and 3P model, and your compliance needs.

2

Architecture

Design the integration, data residency, and where it runs.

3

MVP

Go live with the features you need on day one, then build the rest.

4

Rollout

Onboard vendors and grow.

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Marketplaces built on Mercur

Case study Mercur x Montelink
GreenfieldLegal & tax

Montelink

B2B2C online consultation marketplace for independent advisors and business experts, with a per-minute billing engine and custom expert panel.

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Material Index logo above the marketplace homepage, headed "The Circular Economy platform and marketplace for construction".
GreenfieldCapital Goods

Material Index

Material Index lets contractors, architects and developers buy and sell reclaimed materials, live in the UK and licensed in Australia, the USA, and Spain.

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suplement.io logo above the platform homepage, headed "Launch your supplement brand. In weeks, not months." beside cards for two gummy products.
GreenfieldHealth & personal care

Suplement.io

Suplement.io equips supplement brands with EU-based manufacturing – ready-to-brand products, private-label formulation and compliance – in 20+ EU countries.

Read the case
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FAQ on eCommerce marketplace solution

See how leading brands build their marketplace

Talk to the team behind Mercur – how it works, how other brands build with it, and where it fits for you.

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