Marketplace founders are stuck in the supply–demand cold start with no way to seed either side and prove liquidity

Summary

A founder building a two-sided marketplace for digital products did the recommended groundwork — 50+ one-on-one conversations with creators, personalized outreach instead of mass messaging, better terms for the first sellers, non-exclusive listings — and is still stuck: creators won't invest effort without buyers, and buyers won't show up to an empty shelf. He has no way to know whether 10 sellers is enough, whether he must seed the demand side himself, or how to manufacture the first liquidity that makes the marketplace self-sustaining. The available guidance is a pile of conflicting anecdotes ('seed supply first,' 'let sellers bring their audience'), and there is no tool or service that models a specific marketplace's minimum viable liquidity, simulates seeding strategies, or runs the supply-side acquisition and demand-side bootstrapping for the founder. Founders are left experimenting live with real money and time, launching into an empty market, and quietly abandoning otherwise viable marketplaces. This is a severe, unsolved gap that market builders would pay real money to close, and it is directly a startup-formation problem rather than a well-served enterprise one.