The chicken-and-egg playbook every marketplace founder reuses

Best fit when: you have capital to deploy and the marketplace's unit economics will eventually justify the subsidy. Disastrous when neither is true — you bleed cash forever.

How to know which side is harder: count the natural inbound on each side at zero marketing. Whichever has fewer hands raised is the harder side.

Shape 4: Aggregate existing supply

How it works: scrape, integrate with, or otherwise represent existing supply that already exists elsewhere. Build the demand side; the supply side already has product-market fit somewhere else and you're just channelling it. Examples: Kayak aggregating flight inventory from airline systems; Indeed aggregating job postings; Airbnb's early "we'll list your Craigslist apartment for free" hack.

Best fit when: the supply already exists in some form publicly or via integrations. Be very careful about whether what you're doing is welcomed by the supply (or about to be cease-and-desisted).

Shape 5: Founder-led marketplace

How it works: in the first 90 days, the founder personally handles both sides. They take the supply order, fulfil it manually, deliver to the demand side. The "marketplace" is a Stripe page and a phone number. Examples: Airbnb's early days (founders flew to every host's apartment to take photos); Reddit's early days (founders posted fake content from sock-puppet accounts to seed activity); most enterprise marketplaces start with the founder personally brokering each deal.

Best fit when: you have no liquidity and no capital but you have time. You're using your own time as the subsidy. Doesn't scale past 100 transactions but it tells you whether the marketplace shape works at all.

Picking your shape

Answer these three questions:

1. Is there a single-player version of the product that's useful on its own? Yes → Shape 1.
2. Do you have $50k+ to deploy on subsidies and you've identified the harder side? Yes → Shape 3.
3. Does meaningful supply already exist somewhere else (Craigslist, public listings, APIs)? Yes → Shape 4.

If no to all three:

• Have a tight geography / niche? Yes → Shape 2.
• No? Shape 5. Be the marketplace yourself for 90 days and use the learning to pick a different shape after.

What never works

• "Launch a two-sided marketplace and run paid ads to both sides simultaneously." Bleeds cash on both sides, neither side ever sees enough of the other to retain.
• "Build the world's best marketplace UX and the liquidity will come." Design doesn't beat liquidity. The ugliest marketplace with enough supply beats the prettiest empty one.
• "Wait for organic growth to hit critical mass." Marketplaces don't grow organically from zero; the founder has to make the first 100-1,000 transactions happen by hand.

What to do today

If you're at zero: pick Shape 5. Start brokering. The point is to learn whether the trade is real, not to scale.

If you've done 50-100 transactions and the unit economics survive: pick Shape 1, 2, 3, or 4 based on what you've learned. Don't pick two shapes simultaneously — you'll dilute focus on both.