Poshmark

Poshmark is a North American marketplace for secondhand fashion, built around a social rather than transactional experience — users follow each other, share listings and participate in themed selling events.

That social layer is the platform's distinguishing feature: visibility depends substantially on activity, so sellers who engage regularly move inventory faster than those who simply list and wait.

It handles shipping with prepaid labels and a flat rate, and holds payment until the buyer receives the item.