Definition
A marketplace is a type of platform that connects buyers and sellers to facilitate commercial transactions. The marketplace operator does not own the goods or services being exchanged. Instead, it provides the infrastructure for discovery, matching, trust, and often payment processing, earning revenue through commissions, transaction fees, or subscription charges to sellers.
Marketplaces are a subset of platform business models specifically focused on commercial transactions. Airbnb connects hosts with travelers. Upwork connects freelancers with clients. Etsy connects artisans with buyers. App stores connect developers with users. Each of these businesses owns neither the supply nor the demand. They own the market itself, which is what makes the model so capital-efficient and scalable once the flywheel is spinning.
The defining characteristic of a marketplace is two-sided network effects: more sellers attract more buyers (better selection), and more buyers attract more sellers (more potential revenue). This creates a flywheel that accelerates as the marketplace grows. However, the same dynamic makes early-stage marketplaces extremely difficult. Without enough supply, buyers leave. Without enough buyers, sellers leave. Solving this cold-start problem is the primary challenge for any marketplace PM, and it requires creative strategies for seeding one side of the market.
Why It Matters for Product Managers
Marketplace PMs manage fundamentally different product challenges than single-sided product PMs. Every feature decision affects both sides of the market, and optimizing for one side can harm the other. Making it easier for buyers to compare sellers (good for buyers) increases price competition (bad for sellers). Reducing seller requirements increases supply (good for buyers) but may reduce quality (bad for long-term trust). Marketplace PMs must think in terms of ecosystem health, not just user satisfaction.
The key metrics for marketplace PMs differ from standard SaaS metrics. Liquidity (the percentage of listings that result in a transaction), time to first transaction (for both buyers and sellers), and repeat transaction rate matter more than simple MAU or MRR. A marketplace with 100,000 users but low liquidity is less healthy than one with 10,000 users where transactions happen reliably. Understanding unit economics at the per-transaction level is essential for determining whether the marketplace can be profitable at scale.
How to Apply It
When building a new marketplace, start with the constrained side. Figure out whether supply or demand is harder to attract and focus there first. For most marketplaces, supply is harder because sellers need to invest time creating listings with no guarantee of sales. Seed initial supply yourself if needed (Instacart's early shoppers were employees, DoorDash founders did their own deliveries). Constrain your initial market to one geography, category, or use case to achieve local liquidity quickly before expanding.
Invest heavily in trust infrastructure. Reviews, ratings, identity verification, payment escrow, and dispute resolution are not nice-to-have features. They are the marketplace's core product. Without trust, transactions move off-platform (sellers and buyers exchange contact info to avoid marketplace fees). Build tools that make sellers more successful on your platform than they would be on their own: analytics, promotional features, communication tools, and fulfillment support. Track GMV, take rate, and net revenue alongside competitive moat indicators like supply-side retention and buyer repeat rates. For frameworks on evaluating market opportunities, use the TAM calculator and see the product strategy handbook.