How to Write a YC Application for a Two-Sided Marketplace

This page covers exactly how to frame each application field for a marketplace business, the specific liquidity and density metrics that matter, and the marketplace-specific traps that sink otherwise promising applications.

Before writing a single field, identify the answer to this question: which side of your marketplace is harder to acquire, and what have you done specifically to solve that harder side?

In nearly every marketplace, one side is significantly harder to acquire and retain than the other. For a freelance marketplace, supply (qualified freelancers) is usually the harder side. For a niche B2B marketplace connecting buyers to specialized suppliers, the buyers might be harder to acquire if the suppliers are eager but buyers are skeptical of a new platform. For a marketplace serving an established profession (doctors, lawyers, contractors), the professional supply side often requires more deliberate, manual relationship-building than the demand side.

Your entire application should be organized around demonstrating that you have identified your hard side correctly and have a credible, evidenced plan for solving it — not a generic "we'll grow both sides together" narrative.

50-Character Description

Name both sides explicitly if space allows, or name the harder side specifically if it does not.

Strong examples:

• "Marketplace connecting pharmacy owners and verified distributors"
• "On-demand marketplace for verified home repair contractors"
• "B2B marketplace for surplus industrial equipment"

Avoid generic marketplace language ("Uber for X," "Airbnb for Y") unless the analogy genuinely clarifies the mechanic for an unfamiliar reader — and even then, follow it immediately with the specific supply and demand sides.

Product Description — The Liquidity Story

Structure: [Supply side] + [Demand side] + [The matching mechanic] + [Current liquidity evidence]

"We connect independent home repair contractors (supply) with homeowners needing repairs verified through licensing and insurance checks (demand). Homeowners post a job description with photos; we match them with 3 verified contractors within 2 hours based on specialty and location. We currently have 340 verified contractors across 4 Indian cities and have facilitated 1,200 completed jobs in the last 90 days, with a 94% job completion rate."

That description names both sides specifically, explains the matching mechanic in one sentence, and provides liquidity evidence (completed jobs, completion rate) rather than vanity metrics like total signups.

The Traction Field — Reporting Both Sides Honestly

The single biggest marketplace application mistake is reporting only demand-side metrics (more visible, easier to inflate with marketing spend) while obscuring supply-side health. Report both sides explicitly:

Supply side: "340 verified contractors onboarded. 180 (53%) have completed at least one job in the last 30 days — our measure of active supply."

Demand side: "1,450 homeowners have posted at least one job. 1,200 jobs completed, 94% completion rate."

The match rate — the metric that matters most: "78% of posted jobs receive at least one contractor response within 2 hours. This match rate has improved from 52% three months ago as we've concentrated contractor density in our top 2 cities rather than spreading thin across all 4."

The match rate (or fill rate, depending on your marketplace type) is the single most important marketplace-specific metric and should appear prominently in your traction section. It is the number that tells partners whether your marketplace actually works as a marketplace, independent of how many people have signed up on either side.

The Insight Field — What You Know About Your Hard Side

Your insight should focus specifically on the harder side of your marketplace and what you understand about acquiring or retaining it that competitors do not.

"Every existing contractor marketplace in India requires contractors to bid against each other for jobs, driving prices down and pushing the best contractors away from the platform within months. We pay contractors a fixed referral fee per completed job regardless of job price, which means our best, most in-demand contractors stay active on our platform rather than treating us as a last-resort lead source. Our contractor retention at 90 days is 71%, compared to an estimated 25-30% for bid-based competitor platforms based on contractor interviews."

The Unfair Advantage Field — Supply-Side Relationships

For most marketplaces, the unfair advantage that matters is supply-side access or relationships, since supply is more frequently the harder side to acquire and the side competitors struggle most to replicate.

"Our cofounder spent 4 years running operations for a contractor cooperative covering 200+ contractors across Pune. Those existing relationships gave us our first 80 contractors in 6 weeks — a cold-start problem that would take a competitor 6-12 months to solve through generic recruiting."

Liquidity Metrics

Match/fill rate: Percentage of demand-side requests that successfully connect with supply. The single most important marketplace health metric.

Time to match: How long it takes from a demand-side request to a successful supply-side connection. Faster is generally better, but the right benchmark depends on your category — a same-day home repair match is different from an appropriate timeline for a high-value B2B equipment match.

Repeat usage rate: Percentage of demand-side users who return for a second transaction within a defined window. This is your best signal of genuine product-market fit versus one-time curiosity usage.

Density Metrics

Geographic or category density: Marketplaces typically need a minimum density threshold within a specific geography or category before liquidity becomes self-sustaining. State your current density and your strategy for reaching the threshold: "We have 340 contractors across 4 cities, but our liquidity data shows match rates above 70% only in our top 2 cities where contractor density exceeds 80 per city. We are deliberately concentrating new contractor acquisition in 2 additional cities rather than spreading across 10, based on this density threshold finding."

Supply utilization rate: What percentage of your supply side is actively transacting versus dormant. Low utilization (a large number of registered suppliers with few actually completing transactions) is a red flag partners specifically probe.

Take Rate and Unit Economics

Take rate: Your percentage or fixed fee per transaction, and how it compares to alternatives in your category. Be specific about whether your take rate is sustainable at scale or whether you are currently subsidizing one side to build liquidity.

Contribution margin per transaction: After accounting for any subsidies, incentives, or acquisition costs tied to a specific transaction, what is your actual margin? Marketplaces sometimes show impressive gross transaction volume while losing money on every individual transaction during a subsidized growth phase — be honest about which phase you are in.

Trap 1: Reporting GMV (gross merchandise value) as if it were revenue

GMV is the total value of transactions flowing through your platform. Your actual revenue is your take rate applied to that GMV. Conflating the two — or worse, hoping partners won't ask the difference — is one of the most common marketplace application mistakes. State both explicitly: "GMV of ₹18 lakh over the last 90 days, with a 12% take rate generating ₹2.16 lakh in platform revenue."

Trap 2: Demonstrating growth on the easy side while obscuring stagnation on the hard side

If your demand side is growing 20% month-over-month but your supply side is flat, do not lead with the demand growth number alone. Partners will ask about the other side specifically, and an application that omits this context reads as either naive about marketplace dynamics or deliberately obscuring a weakness.

Trap 3: Treating "chicken and egg" as a problem you'll solve later rather than one you've already solved

Every marketplace founder knows about the chicken-and-egg cold-start problem. What differentiates a strong application is evidence that you have already solved it at small scale — even if that scale is just one neighborhood, one city, or one narrow category — rather than a plan for how you intend to solve it.

Trap 4: Ignoring disintermediation risk

If your marketplace's two sides could plausibly transact directly once they find each other (a common risk for service marketplaces where the contractor and homeowner could simply exchange phone numbers and skip the platform on future jobs), address this directly. What is your specific mechanism for retaining the transaction on-platform — payment processing, ongoing dispute resolution value, insurance/verification you provide, or other genuine value that justifies continued platform usage?