Epidemic Sound - Website with licensed music to use in youtube videos
Zapsplat - Zapsplat Royalty free music is a website that covers an extensive list of royalty-free music, making you download over 85000 sounds effects in a very format like Mp3, FLAC, M4A, WAV, ACC, and many others.
Mixkit Free Sound Effects - Mixkit Free Sound Effects is a website that is introduced for incredible free sound effects, making you use in your cinematic projects without any hurdle.
Storyblocks - You bring the vision, we bring the royalty-free stock. Choose from millions of images, video footage clips, After Effects templates, and audio tracks.
Sample Focus - The easiest way to find the perfect audio sample
Freesound - The Freesound Project is a collaborative database of Creative Commons licensed sounds.