How to cut an MP3
Drop in a song or a recording and its waveform is drawn. Drag the handles at each end to the part you want, or type Start and End as seconds (12.5) or minutes and seconds (1:02.25). Dragging across the waveform draws a new selection, and a click moves the playhead. Play selection plays the cut; Save MP3 saves it.
Clean starts and ends
Trim silence at the ends moves the handles in past near-silence (below −50 dB), leaving 10 milliseconds so a soft first note is not clipped. A cut in the middle of a sound can start or end with a click; a Fade in or Fade out of half a second hides it.
To the millisecond
Times are shown to a thousandth of a second. A focused handle moves a hundredth at a time with the arrow keys, a tenth with Shift, and Home and End send it to the ends. Space plays and stops the selection from anywhere on the page.
Questions
Does cutting an MP3 lower its quality?
A little. Rather than copying the MP3's frames, this cutter decodes it and encodes the part you keep again, which is what lets it fade and change the volume. At 192 kbps or more the difference is hard to hear; for an exact copy of the cut, save it as WAV.
Can I cut out the middle and keep both ends?
No. It keeps one part, from Start to End. Save the beginning and the end as two files if you need both.
Which files can it cut besides MP3?
Anything your browser can play: WAV, M4A and AAC, OGG, Opus, FLAC and AIFF, and the sound of an MP4, MOV or WebM video. Safari cannot read OGG files.