Rasmus Sorensen

Founder of Prometora. Writing about marketplace building, with data from running the platform.

growth

I sell marketplace apps now. I'll still talk most of you out of one.

Aug 18, 2026

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3 min read

I sell marketplace apps now. I'll still talk most of you out of one.

The 30-second test that tells you whether a mobile app grows your marketplace or just burns a few thousand dollars.

Rasmus Sorensen

operations

Aug 16, 2026

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4 min read

Who pays for the shipping label?

Shipping on a marketplace isn't a logistics problem. It's a fourth money flow - and if you don't design it, the answer to the title is: you.

Rasmus Sorensen

data

The AI engines name my competitor in 99% of answers. Me: 17%.

Aug 6, 2026

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3 min read

The AI engines name my competitor in 99% of answers. Me: 17%.

I asked ChatGPT and Claude the twelve questions my buyers actually ask, three times each, and counted every brand they named. This is day one of the scoreboard.

Rasmus Sorensen

postmortems

Everything I've built (half of it is dead)

Aug 2, 2026

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4 min read

Everything I've built (half of it is dead)

Ten projects, one exit, five shutdowns - and the pattern I only saw afterwards.

Rasmus Sorensen

growth

Nobody brags about their B2B marketplace. They just make money.

Aug 2, 2026

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3 min read

Nobody brags about their B2B marketplace. They just make money.

Why B2B marketplaces quietly outperform consumer ones - and what B2B founders actually ask for, ranked from the requests that land in my inbox.

Rasmus Sorensen

payments

Don't interrogate sellers before they've earned a cent

Jul 31, 2026

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3 min read

Don't interrogate sellers before they've earned a cent

The deferred onboarding pattern for Stripe Connect: let sellers sell first, verify later - plus the EU legal nuance nobody warns you about.

Rasmus Sorensen

data

Jul 30, 2026

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3 min read

The bots showed up on day one

I logged every AI crawler on 13 real marketplaces for a week: 604 visits from 11 bots - none of them visible in normal analytics.

Rasmus Sorensen