Qbittorrent | Ed2k

However, a niche community still keeps ED2K alive because of one feature: As long as one person has a file, Kad can find it. BitTorrent dies the moment the last seeder leaves and the tracker goes offline. ED2K files from 2003 are still downloadable today.

If you want one app for everything, older "all-in-one" clients like qbittorrent ed2k