Most marketplaces are two-sided: buyers and sellers. Stripe powers the money, the platform takes a cut, everyone's happy.

A three-sided marketplace is a different beast. We needed sellers to list products, creators to promote them, and buyers to purchase — with money, attribution, and incentives flowing correctly between all three on every single transaction.

This is how we built Peddlum, the architecture decisions we made, and the things that almost broke us.

The Core Problem
In a two-sided marketplace, a sale is simple: buyer pays seller, platform skims a fee, done.

In our model, a single sale has to:

Charge the buyer via Stripe
Split revenue between platform, seller, and creator
Attribute the sale to the right creator's tracking link
Apply the creator's tier multiplier
Update three different wallets atomically
Trigger fulfillment (file delivery OR SaaS webhook)
Fire notifications to all three parties
Get any step wrong and someone is underpaid. The hard part isn't the code — it's making sure the invariants hold under failure.