ccMixter
ccMixter focuses on audio material and tracks for remixing.
What it does
ccMixter centers on community tracks and material made for remixing.
When to use it
For a podcast opening, test how a vocal sample sits with an instrumental track.
Visit ccMixter official site
Bensound
Bensound focuses on music browsed by mood and intended use.
Epidemic Sound
Epidemic Sound focuses on music for videos, streams, and shows.
Freesound
Freesound focuses on community-shared sound samples and recordings.