An example of a north star metric for a marketplace product should capture the value created for both sides of the market simultaneously — the most common choice is Gross Merchandise Value (GMV) per active user or successful transactions per active buyer per month, because a marketplace north star that only captures one side of the market will create policy and product decisions that optimize for supply at the expense of demand or vice versa.
Marketplace north star selection is uniquely challenging because marketplaces have two customers — buyers and sellers — whose needs are sometimes in tension. A north star that only reflects seller activity will systematically deprioritize buyer experience investments, and vice versa.
Why Marketplace North Stars Are Harder
In a single-sided product, the north star reflects one customer's value. In a marketplace, you must capture:
- Liquidity: Is there enough supply for buyers and enough demand for sellers?
- Transaction success: Are the matches the marketplace makes actually completing?
- Repeat behavior: Are buyers and sellers coming back, which signals genuine value creation?
A north star that captures all three dimensions is the goal.
North Star Examples by Marketplace Type
Transactional Marketplace (Airbnb, Etsy model)
Recommended north star: Successful bookings per active buyer per month
Why: "Successful" filters out failed transactions and cancellations. "Per active buyer" normalizes for acquisition volume. "Per month" captures repeat behavior.
Why not raw GMV: A marketplace can grow GMV by increasing prices (average order value) while the number of successful transactions declines — meaning fewer buyers are finding what they need. GMV growth masked by price inflation is not health.
Services Marketplace (Upwork, Fiverr model)
Recommended north star: Completed engagements per active client per quarter
Why: "Completed" confirms the service was delivered and the marketplace functioned. "Per active client per quarter" normalizes for size and reflects repeat purchase intent.
Why not total revenue: Revenue growth can come from a small number of very large clients while overall marketplace health (breadth of usage) declines.
Two-Sided Marketplace with Physical Goods (Amazon Marketplace model)
Recommended north star: Repeat purchase rate at 60 days
Why: Repeat purchase is the strongest signal that the marketplace created genuine value — the buyer found what they needed, the transaction completed, and the product delivered on expectation. 60 days is long enough to measure real repeat intent, not just impulse.
According to Lenny Rachitsky's writing on marketplace metrics, the most common marketplace north star mistake is choosing a metric that reflects platform activity (listings, messages, sessions) rather than value creation (successful transactions, repeat buyers) — activity metrics can grow while marketplace health declines if listings are low quality or buyer intent is weak.
The Marketplace North Star Framework
Step 1: Identify your marketplace's core value exchange
→ What does a buyer get when the marketplace works well?
→ What does a seller get when the marketplace works well?
Step 2: Find the metric that confirms both sides got value
→ A successful transaction is usually the common event
Step 3: Normalize for buyer base size
→ Per active buyer / per active seller removes acquisition noise
Step 4: Add a repeat behavior signal
→ Repeat transactions signal genuine value, not one-time curiosity
Supporting Metrics by Marketplace Side
Supply-Side Health
- Active seller rate: % of registered sellers who listed in the last 30 days
- Listing quality score: % of listings with complete information, photos, competitive pricing
- Seller NPS: Are sellers satisfied enough to continue listing?
- Inventory depth: Average number of viable options per buyer search query
Demand-Side Health
- Search-to-transaction rate: Of buyers who search, what % complete a transaction?
- Buyer repeat rate: % of buyers who transact in 2 consecutive months
- Time-to-match: How long does it take a buyer to find what they're looking for?
- Buyer NPS: Are buyers satisfied enough to return?
According to Shreyas Doshi on Lenny's Podcast, the supply-demand balance metric is the most underrated measurement challenge in marketplace products — a marketplace can show excellent demand metrics while supply is quietly degrading, and the degradation only becomes visible when buyers start failing to find what they're looking for, which by then has already damaged buyer NPS and repeat rates.
Guardrail Metrics for Marketplaces
Marketplace north stars must be protected by guardrail metrics:
- Transaction dispute rate: Optimize for GMV without a dispute guardrail and you'll match buyers with low-quality sellers
- Seller churn rate: Optimize for buyer metrics without seller health guardrails and supply degrades
- Fake listing rate: Growth metrics can be gamed by fake listings that inflate supply without improving liquidity
According to Gibson Biddle on Lenny's Podcast, the marketplace products that fail fastest are those that optimize their north star without liquidity guardrails — a marketplace with 10 million listings and 10 million searches but a 5 percent transaction completion rate is not a marketplace, it is a search engine for unavailable products.
FAQ
Q: What is a good north star metric for a marketplace product? A: Successful transactions per active buyer per month, or GMV per active user. The key is choosing a metric that reflects successful value exchange for both marketplace sides, not just activity volume.
Q: Why is GMV a poor north star metric for marketplaces? A: GMV can grow through price increases while the number of successful transactions declines. It also doesn't capture repeat behavior, which is the most reliable indicator of genuine marketplace value creation.
Q: What is liquidity in a marketplace product? A: The probability that a buyer can find what they're looking for and a seller can find a buyer for what they're offering. Low liquidity means buyers search but don't transact, and sellers list but don't sell.
Q: How do you measure marketplace health beyond the north star? A: Track supply-side health (active seller rate, listing quality, inventory depth) and demand-side health (search-to-transaction rate, buyer repeat rate, time-to-match) as supporting metrics alongside the north star.
Q: What guardrail metrics should a marketplace track alongside its north star? A: Transaction dispute rate, seller churn rate, and fake or inactive listing rate. These prevent optimizing the north star in ways that degrade marketplace quality or supply reliability.
HowTo: Define a North Star Metric for a Marketplace Product
- Identify the core value exchange in your marketplace — what a buyer receives when the marketplace works well and what a seller receives — so the north star can capture both
- Find the metric that confirms both sides received value in the same event — typically a successful completed transaction rather than a listing or a search
- Normalize the metric for user base size by expressing it per active buyer or per active seller to remove the noise from acquisition volume changes
- Add a repeat behavior signal by measuring the metric over a time window — per month or per quarter — that captures whether users return, which is the strongest indicator of genuine value creation
- Define supply-side and demand-side supporting metrics including search-to-transaction rate, active seller rate, buyer repeat rate, and inventory depth per search query
- Set guardrail metrics on transaction dispute rate, seller churn, and fake listing rate to prevent north star optimization from degrading marketplace quality and long-term liquidity