A lot falls under the domain of music editing. You can create ringtones or cut out parts of songs that you don’t want. Music editing software can also remove noise from a song, merge multiple music files into one, lower the overall sound, edit your voice, add virtual instruments, etc.
After trying nearly two dozen options, I’ve compiled this list of the best music editors that can do all of those things. Some are free, and others have a free trial.
Many music editors can convert a song into a ringtone, but I prefer MP3Cut.net because it works online and doesn't have many confusing features.
Upload the song from your computer, a URL, or your Google Drive or Dropbox account, then trim out the ends you don’t want in the ringtone. There’s also an equalizer section to play with, plus options to adjust volume, speed, and pitch.