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

I've spent the first three issues telling you how to run marketplace onboarding, payments, and B2B pricing. Fair question: who is this guy, and why would he know?

So this issue is the receipts. Everything I've built, including the dead ones. Especially the dead ones.

NordicMugs - a marketplace for Moomin mug collectors, launched in 2022. If you're not in that world: rare Moomin mugs are serious collector items, some trading for up to 5,000 EUR. Still running, still gets orders every month, basically on autopilot. It taught me what "done" software feels like: it just runs.

My Spare Desk - a marketplace for renting out your spare desk at home, turning your apartment into a co-working space whenever you felt like it. I built it in a couple of months post-Covid, when I was working remotely myself and half the world had an extra desk standing around. Launched on WhatsApp, Reddit, Product Hunt, and Hacker News. Reddit did not hold back. And underneath the harsh comments were real flaws: people who said they'd join didn't, remote workers worried about staying productive in a stranger's home, and for hosts the money never justified the effort - the Airbnb incentive math doesn't shrink down to a desk. I closed it. Dead.

NinjaBuzz - a marketplace for buying and selling host-read podcast ads, co-founded with Mads. September 2021 to February 2022. Podcasters listed their show and a price for a host-read spot, advertisers browsed the library and booked in minutes, we took 15% through Stripe. I launched it on r/Podcasting on September 8, 2021 (the post is still up), and within months we had more than 280 podcasters listed and 50+ paid transactions. A working, liquid marketplace. We shut it down anyway, on purpose: once we did the math on small ad spots and a 15% take, it was never going to become as big as we'd imagined. Six months, one complete marketplace, one expensive lesson - liquidity is not the same as a market.

You Are My Star - a side project from 2023: buy a star and give it to someone you love, or sell your stars on - all traded in a play currency. Still alive. Not everything has to be a business.

SerpMaze - an SEO keyword tracker for solopreneurs, built from August 2022 and sold on Acquire.com in 2024. The one exit on this list: a focused tool that did one thing reliably, and somebody paid to take it over.

My Ebook Page - a no-code landing page builder for ebook authors, from around 2020. Dead.

Focus on Listening - a transcription service, co-founded. July 2021 to July 2022. Audio to text in more than 10 languages, with speaker identification. This one didn't die from lack of users - it died from lack of capital. Transcription at that quality needed a lot of data, we pitched VCs, the money didn't come, and we shut it down. Two months later, OpenAI released Whisper and made the data problem we couldn't fund essentially free. Dead, and in hindsight, mercifully early.

15 Minute Meetings - a Covid-era scheduler that capped every meeting at 15 minutes, for when the whole world suddenly moved to back-to-back video calls. Dead. A strong opinion in search of a market.

Speed Build Marketplace - a marketplace boilerplate I made in 2024: the codebase I kept rebuilding for every project above, packaged so others could start from it. More than 50 marketplace builders have bought it and are using it, and it's still alive today. It's also the bridge in this story: watching who bought it made one thing obvious - plenty of people want to run a marketplace, far fewer want to own the code underneath it. That observation became Prometora.

(In between all of this there were normal jobs too - most recently building a real-time analytics product for newsroom editorial teams. Not every year of a builder's life is a startup, and that's fine. The full timeline is on my LinkedIn.)

Prometora - the marketplace platform I run today, launched October 2025. The reason this newsletter exists. It's where every lesson below is now encoded in software.

Line them up and the lesson isn't "work harder" or "pick better ideas". It's this:

1. The marketplaces didn't die from missing features. NinjaBuzz reached 280+ podcasters and 50+ transactions - real liquidity - and we still shut it down, because 15% of small ad spots was never going to compound into a company. My Spare Desk never got that far: demand stayed hypothetical (people who said they'd join didn't) and the host incentives were too weak. Between the two of them: working software was never the bottleneck, and liquidity isn't the same as a market.

2. The tools died on distribution - or on capital. My Ebook Page and 15 Minute Meetings were fine products with zero channel; building was the fun part, so building was the part I did. Focus on Listening had the opposite problem: the building itself needed money we couldn't raise.

3. The focused one was the valuable one. SerpMaze did one thing reliably, and it's the only project on this list that ended in a wire transfer instead of a shutdown email.

Ten projects to learn three sentences. That's the tuition model of indie building: the lessons are cheap to read and expensive to believe.

Prometora ships with opinionated defaults instead of a blank canvas, and this list is why. When a founder launches a marketplace on it, the defaults quietly assume everything above: that your scarce resource is supply and demand, not features. That onboarding friction kills sellers (issue #2). That the boring, unglamorous plumbing - payments, payouts, commissions - is where the value is.

I got those opinions the expensive way. You're getting them for free.

If you're somewhere in the middle of your own list right now: the projects that die don't count against you. They only go to waste if the next one doesn't inherit anything.

- Rasmus

P.S. This is issue #4 of The Marketplace Guy. I build Prometora, a marketplace platform, and this is where I write down what running the infrastructure under many marketplaces teaches me. If someone forwarded you this: you can subscribe at https://themarketplaceguy.beehiiv.com/