CUETools - CUETools is a suite of tools for converting and verifying lossless CD rips.
Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
FlacSquisher - FlacSquisher converts a library of Flac files to MP3, Opus, or Ogg Vorbis format.
FL Studio - Image-Line's FL Studio, now on it's 12th version, is a well-known music production suite and the most popular beat processor on the market, due no doubt to its longevity. Read more about FL Studio.
dBpoweramp - dBpoweramp contains a multitude of audio tools in one: CD Ripper, Music Converter, ID Tag Editor...
MixPad - MixPad is free music Music Mixer and Recording software designed for easy audio production.