Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Spek - Spek helps to analyse your audio files by showing their spectrogram.
GarageBand - GarageBand is a fully equipped music creation studio for Mac
SoX - Sound eXchange is a command line utility that can convert various formats of computer audio files...
Adobe Audition - Mix, edit, and create audio content in Adobe Audition CC with a comprehensive toolset that includes multitrack, waveform, and spectral display.
AudioMass - A full-featured web based audio editor 🎶