Audacity

There are many tools in this section, but as far as some are very comprehensive and efficient. It is a free, open source software that works directly with sound waves graphics, GNU licensing for recording and editing audio. It can convert files

It supports most audio formats, such as wav, mp3, ogg, wma, ac3, flac and aiff. This includes all basic editing tools such as Cut, Copy, and Delete. Thanks to the amount of available filters and effects, Audacity is much more versatile than it seems first.

In addition to all this, it lets you adjust the level of the audio track, change the shape of the wave, adjust your needs or add all kinds of post processing effects. Your power is likely to apply changes to any section of the audio file, as well as its multi-track edit. You can even apply a filter that removes a song's voice.

If this is not enough, you can add all 32-bit external VST plugins, and reproduce MIDI files.