Musopen: Musopen is a free music library with over 5,000 high-quality classical music recordings, all of which are available for download.
NoiseTrade: NoiseTrade is a site where artists offer their music for free in exchange for an email address. You can find a variety of genres on NoiseTrade, including rock, pop, electronic, and folk.
Free Music Archive: The Free Music Archive is a collaboration between the WFMU radio station and the Internet Archive. The site features over 150,000 free-to-download live concerts and studio recordings from both well-known and independent artists.
Jamendo: Jamendo is a community of independent musicians who share their music for free. You can find a wide variety of music on Jamendo, including rock, pop, electronic, and folk.
Amazon: Amazon offers over a million free songs that can be downloaded from its website or mobile app. To access these free songs, you must be an Amazon Prime member, but you can sign up for a free trial if you are not already a member.