Free MP3 Cutter and Editor (portable) v2.8

Free MP3 Cutter and Editor is a simple tool for editing and cutting MP3 files, available as freeware.

You can easily make a selection of the audio stream, delete it or delete the unselected parts of the file. You can change volume, including maximizing it as high as possible without distortion. You can create a fade in effect or fade out effect too.

You can also convert mono tracks for stereo output, or mix multiple channels into one mono track.

Definitely a great tool considering it is freeware. This portable version doesn't require an installation.