Adding a marketplace to an existing Shopify store
You do not have to replatform to sell third-party inventory. Here is the additive path.
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A customer checks out once. Behind that single payment there may be four vendors, three shipping origins, two tax jurisdictions and a platform commission. Every one of those has to reconcile — and keep reconciling through refunds, partial cancellations and chargebacks.
The model
- The customer order is captured as one payment intent
- Mercur derives per-vendor sub-orders, each with its own fulfilment state
- Commission and fees are computed per line, not per order
- A double-entry ledger records every movement, so the books balance at any point in time
Why the ledger matters
Without one, a refund on a multi-vendor order becomes guesswork. With one, every payout has a traceable origin, and reconciliation is a query rather than a spreadsheet.
