With a world’s worth of secondhand and used clothing available, resale platforms like Depop are connecting buyers and sellers of even the most niche and specific styles across large distances.

This as-told-to essay is based on a transcribed conversation with Danielle Mass, a 25-year-old founder from London, about starting a Depop shop. It has been edited for length and clarity.

Platforms like Depop, eBay and Vinted, which launched in Ireland late last year, have surged in popularity, helping to democratise selling second-hand clothes and ushering in an anything-goes ...