Audio trimmer

Cut sound to the part you want, to the millisecond, with fades, on your device. Free, with no account or uploads.

Drop a sound to trim

Choose the part to keep, or cut parts out, to the millisecond, with fades so nothing clicks. MP3, M4A, Opus, FLAC, WAV and videos, on your device. You can also paste with ⌘V or Ctrl+V.

Choose files

MP3
M4A
Opus
FLAC
WAV
AIFF
MP4
MOV
WebM

Stays on your device · up to 50 files at once

This page is the Audio editor, opened for trimming.

What you can do

Trim, fade and change the volumeTo the millisecond, on a waveform you can zoom; every edit can be undone, and your file is never changed.
Every common formatMP3, M4A (AAC), Opus, FLAC, WAV and iPhone ringtones, from those and from AIFF, Ogg and the sound of videos.
Loudness to a standardMeasured as ITU-R BS.1770 does, normalized to −14 LUFS or another target, with a true-peak limiter so nothing clips.
Sound out of videoKept exactly as it is, without being encoded again, whenever the format allows; or converted to the format you choose.
Checked before you downloadEvery file written is opened again and listened to: its length, rate and channels are held against what you asked.
Many files at onceTags and cover art kept, gapless MP3s, a size limit if you need one, and everything in one ZIP.
Nothing is uploadedYour files are read and written in this browser. No account, no limits.

A little help along the way

Follow the steps below. Every option is explained underneath.

Add the fileDrop it, choose it or paste it: MP3, M4A, Opus, Ogg, FLAC, WAV, AIFF, or a video.
Choose the partDrag across the waveform, or type the start and end. Zoom in to be exact, and play the selection to hear it.
Keep it or cut it outKeep only this, or Cut out, and fade the ends if you like. Undo whenever you change your mind.
DownloadThe result is written in the file's own format, unless you choose another, and checked before you download it.

Every option explained

Choosing a part: Drag across the waveform, drag a selection's edge to move it, or type its start and end (as 7.25, 1:07.25 or 1:02:03). On the waveform, I and O start and end the selection at the playhead. Zoom in to choose to the millisecond: the buttons, Ctrl or ⌘ with the wheel, or a trackpad's pinch.
Keep only this, Cut out: Keep only this keeps the selection and drops the rest; Cut out takes the selection away and closes the gap. Wherever the sound was cut, it fades out and in over 4 milliseconds, too short to hear as a fade and enough to take away the click a cut can make.
Fades: Choose the part to fade over and press Fade in or Fade out. Even fades at a steady rate; Smooth keeps more of the sound until late; S-curve starts and ends softly.
Silence and volume: Silence makes the selection silent and keeps its length. Volume makes the selection, or all of it when nothing is chosen, louder or quieter by up to 24 dB. Louder can clip: listen before you download. Measuring and matching loudness comes in a later version.
Edits and undo: Your file is never changed. Each edit is a step in the list; the result is written from your file and the steps, so you can undo, redo or start again at any time. Each file in the list keeps its own edits; the format settings are shared.
Playing: Play and Play the selection play the sound as edited: cut parts are skipped and fades heard. This is a preview played from your file; the file written is exact to the sample and is checked. Loop repeats what is playing.
Encoded again: An edited sound is always encoded again: MP3 and AAC hold sound in blocks of about a fortieth of a second, so copying them could not cut where you chose. FLAC and WAV keep every sample.
Keys: listening: Space or K: Play or pause. P: Play the selection. ←: Move the playhead back 0.1 s. →: Move the playhead on 0.1 s. Shift + ←: Move the playhead back 1 s. Shift + →: Move the playhead on 1 s. J: Back 5 s. L: On 5 s. HOME: Go to the start. END: Go to the end.
Keys: choosing a part: I: Start the selection at the playhead. O: End the selection at the playhead. Ctrl or ⌘ + A: Select all of it. Esc: Clear the selection. M: Add a marker at the playhead.
Keys: editing: DELETE or BACKSPACE: Cut the selection out. Ctrl or ⌘ + Z: Undo. Ctrl or ⌘ + Shift + Z or Ctrl or ⌘ + Y: Redo.
Keys: zoom: + or =: Zoom in. -: Zoom out. 0: Show all of it.
Silence at the ends: Finds the silence at the start and the end of the sound as edited (under the level chosen, -60 dBFS, -50 dBFS, -40 dBFS) and keeps the sound between, leaving 0.1 s of each. It is one step, undone like any other.
Long pauses: Shortens every pause inside the sound longer than the length chosen (0.5 s, 1 s, 2 s) to 0.4 s, all in one step. Each cut is faded, so nothing clicks.
Same as the file: Keeps the file's own sound as it is, without decoding and encoding it again: AAC goes into an M4A, MP3 stays MP3, Opus and Vorbis go into Ogg, FLAC stays FLAC and plain samples become a WAV. Nothing is lost and it takes a moment. When the rate, the channels or a size limit you chose mean the sound must change, it is encoded again in its own kind; sound that cannot be kept (such as AC-3 from a film) becomes AAC, and the page says so.
MP3: Plays everywhere. Written with LAME at a constant bitrate, with the header that tells players the encoder's delay and padding, so the file is exactly as long as the sound. Below 32 kHz an MP3 holds at most 160 kbit/s.
M4A (AAC) and M4R: Smaller than MP3 for the same quality, and played by every phone and computer. Written with your browser's own AAC encoder, or one that comes with the page when it has none. The encoder's priming is measured and an edit list written, so the sound starts and ends where it should. M4R is the same for an iPhone ringtone, which can be at most 40 seconds long (an alert tone 30).
Opus: The best quality for its size, voice above all. It is always written at 48 kHz. Browsers, Android, VLC and recent Apple devices play it.
FLAC and WAV: Lossless: every sample is kept. FLAC is about half the size of WAV. Choose 16-bit (CD quality), 24-bit, or for WAV 32-bit floating point; FLAC holds at most 24 bits.
Quality: Small, Balanced or High set the bitrate for each format (MP3 96, 192 or 320 kbit/s; AAC 96, 160 or 256; Opus 48, 96 or 160), less for mono. Custom lets you pick the bitrate. These numbers are KeepSimp's own choices.
Sample rate and channels: Keep the file's own, or choose one. When a format cannot hold the rate asked, the nearest it can is used and the page says so. Lossy formats here are mono or stereo, so surround sound is mixed down to stereo for them.
Tags and cover art: Title, artist, album, year, genre and the cover picture go into the new file where its format holds them. Switch it off to write none.
File size limit: MP3, M4A and Opus are written at the highest bitrate that keeps each file under the limit, with room for the container; the page says what it chose. Lossless formats cannot be made to fit a size.
The check: Every file written is opened again and decoded from start to end. Its length, sample rate and channels are held against what was asked, an MP3's size against its bitrate, and a file that came out silent is caught. If something is not as asked, the page says what.
Files the browser cannot read: Some browsers' decoders lack a kind of sound (Safari's lacks FLAC in some places). The page then decodes it with the browser's own player, which plays more kinds, and goes on. AIFF is read by KeepSimp itself. A file nothing here can decode says so.
Privacy: Files are read and written in this browser and never uploaded. There is no account and no limit on how many you convert.

Read the step-by-step guide