FindSounds (Search the Web for Sounds) https://findsounds.com. Source: almost 2 years ago

Tunetank.com - free audio library (has paid version as well). Source: almost 2 years ago

I've used music from tunetank.com, specifically "Evening Wind" and "Happiness Happens", and the video got flagged for these. Despite the site claiming the songs can be freely used in Youtube videos with attribution. The same thing happened when I was using music from pixabay.com. Source: almost 2 years ago

You can search on YouTube for "copyright free music". There are a lot of artists and labels (like NoCopyrightSounds) which allow usage of their songs as long as credit is given. If you want to know a seperate website then I know of TuneTank. Not all are "free", for some you would have to opt for the monthly subscription. Nontheless, they have more than enough good music offered for free. Source: about 2 years ago

Tunetank.com has a great selection of free music you can use without paying royalties. You just have to give credit in the video description. Source: about 2 years ago

And... So many places for music. https://tunetank.com/ is decent, as is YouTube's own audio library. Source: over 2 years ago