It's a desktop client for soulseek: https://github.com/Nicotine-Plus/nicotine-plus
Install, login/register, share your data then search. Filter the results by file format, sort by download speed etc. Soulseek is a very old file sharing platform, work the same way since 2001. A lot of peers don't allow downloading from them if you don't share anything.
For Android I found SeekerAndroid, never used it.