AllMusic
allmusic.com
Browse by genre, mood, decade or who played on it
Sound & Signal
Twenty years of listening data, turned into neighbours
last.fm
Coffee break · Works anywhere
Free, no sign-up · online since 2002
Last.fm has been logging what people play since 2002, and those scrobbles power its similar-artist pages, tag radio and charts reaching back two decades. Any artist page shows which acts their listeners also play, ranked by genuine overlap rather than by label promotion.
Similar-artist lists are built from what real listeners queued up next, which is why they include the unfashionable neighbour a curated playlist would drop.
Keep going
Picked for a shared category and overlapping vibe, not for popularity.
allmusic.com
Browse by genre, mood, decade or who played on it
folkways.si.edu
The US national collection of folk and world recordings
discogs.com
A catalogue of very nearly every record ever pressed
gnoosic.com
Name three bands you like and it guesses the fourth
music-map.com
Type one band, get a constellation of adjacent ones
whosampled.com
Every sample, cover and remix, traced to its source