PAID sites: you will need to pay for a subscription or per song to use music on these sites. Generally music on paid sites is more ‘popular’ music, and has a greater selection than on free sites. It is best if you just click on the links if you would like to check out the pricing.
Soundstripe (Chris Oates): www.soundstripe.com
Epidemic Sound (Chris Oates): https://www.epidemicsound.com
Audio Jungle (Chris Oates): https://audiojungle.net
Music Bakery (Chris Oates): https://.musicbakery.com
FyrFly (Lorelei Hoffarth): https://www.fyrfly.com/
Triple Scoop Music (Lorelei Hoffarth): https://triplescoopmusic.com/
FREE MUSIC sites: sites where you can download music for free. You will need to check the usage rights on each song and some of these sites contain music which is free as well as music that you must pay for. Also read up on whether you need to credit the authors in your slide show.
Bensound (Chris Oates and Lorelei Hoffarth): https://www.bensound.com/
Pixabay (Chris Oates): https://pixabay.com/music/
You Tube Audio Library (Chris Oates): I think you need to be logged into your you tube account to access this, so I can’t provide a direct link. Just look under the menu for Audio Library once you log in.
Free Music Archive (Chris Oates): https://freemusicarchive.org/
Silverman Sound (Chris Oates): https://www.silvermansound.com/