Can you sell old keys?

Excuse me, I'm curious about something. I've come across some old keys that I'm no longer using, and I was wondering if it's possible to sell them. Do you have any experience with selling old keys, or do you know of any reputable platforms or marketplaces where I could potentially list them for sale? I'm not sure if there's a demand for them, but I figured it's worth asking. Any information you could provide would be greatly appreciated.