Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
GSnap - With GSnap you can get an auto-tune effect.
Adobe Audition - Mix, edit, and create audio content in Adobe Audition CC with a comprehensive toolset that includes multitrack, waveform, and spectral display.
Celemony Melodyne - Celemony Melodyne is the perfect quick and easy tool for all your tuning needs.
GarageBand - GarageBand is a fully equipped music creation studio for Mac
Antares Auto-Tune Pro - Auto-Tune Pro by Antares is the latest and enhanced version of Auto-Tune that offers Auto Mode to correct pitch and Graph Mode for step-by-step modifications of time and pitch.