Ask HN: Where do you sell your side projects?

There's Flippa https://www.flippa.com/ and you'll find more with a bit of googling.

But those are platforms for selling "online business" not "side projects".

People who buy want ROI (Return On Investment). They buy money-making business for some multiple of monthly revenue hoping that over time they'll make more than they spent.

It might be just a careless use of terminology on your part.

Or it could be fundamental misunderstanding of how the world works.

No one buys "side projects". Don't try to sell "side projects" because you can't.

People buy businesses. A business makes money. There are people who will buy a money-making business.

Some side projects could also be money-making businesses but not all of them are.

From those I know who have sold their side projects, the buyers usually came to them. I'm not aware of a marketplace for this.