hello,
Here are some sites I have used to find music for my games:
http://dig.ccmixter.org/
http://freemusicarchive.org/
http://incompetech.com/music/
https://audioluck.com/free.html
And of course: http://soundimage.org/ from Construct colleague Eric Matyas.
For these links apply:
Free to download.
Can be used in commercial projects.
Credit when you use a song.
For fun:
These 2 websites have tracks that are algorithmically generated.
http://computoser.com/
http://www.fakemusicgenerator.com/