I wouldn't really call it a traditional online shop, more like a file shop. They don't sell anything physical, only digital. If you've created a file on your computer that other people want, you can sell it on Gumroad. Depending on what you're trying to sell, there might be a better platform for the purpose (like Bandcamp for music), but Gumroad is the only one I'm aware of that's intentionally generic to fit many purposes (even if imperfectly).

They also don't do shit like putting DRM on ebooks and you can set the minimum price to zero to turn it into a tipping platform (free download, but with an optional payment).