How to Build a Multi-Vendor Marketplace in Next.js
A practical guide to architecting a multi-vendor marketplace with Next.js, including vendor onboarding, product listings, M-Pesa payments, and commission logic.
Introduction
Building a marketplace like TumiaTen taught me more about Next.js architecture than any other project. A multi-vendor marketplace involves multiple user roles, payment splitting, and real-time inventory management. This guide walks through the core architecture decisions.
What Makes a Marketplace Different
A standard e-commerce store has one seller. A marketplace has many. This changes your entire data model and payment flow — every product belongs to a vendor, and every sale needs commission deducted before the vendor receives their payout.
1 — Database Schema
model Vendor {
id String @id @default(cuid())
name String
email String @unique
products Product[]
createdAt DateTime @default(now())
}
model Product {
id String @id @default(cuid())
title String
price Float
stock Int
vendorId String
vendor Vendor @relation(fields: [vendorId], references: [id])
}
model OrderItem {
id String @id @default(cuid())
orderId String
productId String
vendorId String
quantity Int
price Float
commission Float
}2 — Commission Logic
const COMMISSION_RATE = 0.10 // 10% platform fee
const orderItems = await Promise.all(
items.map(async (item: any) => {
const product = await db.product.findUnique({ where: { id: item.productId } })
const subtotal = product!.price * item.quantity
const commission = subtotal * COMMISSION_RATE
return {
productId: item.productId,
vendorId: product!.vendorId,
quantity: item.quantity,
price: product!.price,
commission,
}
})
)3 — M-Pesa Integration
// On successful M-Pesa callback
await db.order.update({
where: { id: orderId },
data: { status: "paid", mpesaRef: receiptNumber }
})
const vendorGroups = groupBy(order.items, "vendorId")
for (const [vendorId, items] of Object.entries(vendorGroups)) {
await sendVendorNotification(vendorId, items)
}Conclusion
A multi-vendor marketplace is complex but rewarding. Get the data model right from day one — everything else follows. If you are building a marketplace and need help with the architecture or M-Pesa integration, reach out.
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