Join audio

Join sound files into one, in your order, with gaps or crossfades and chapters, on your device. Free, with no account or uploads.

Drop the files to join

Into one, in the order you set, straight on, with silence between or crossfaded, with a chapter for each. MP3, M4A, FLAC, WAV, the sound of videos and more, 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 joining files.

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 filesDrop them, choose them or paste them: MP3, M4A, Opus, FLAC, WAV, AIFF or the sound of videos.
Put them in orderMove each up or down. Trim or edit any of them first if you like.
Choose how they meetStraight on, with silence between or crossfaded; the format, and Normalize loudness to make them match.
Join and downloadThe joined file is written, checked and ready, with a chapter for each file in an MP3 or M4A.

Every option explained

The order: Files join in the order of the list; move each up or down with its arrows. Each joins as you edited it, so trim, fade or cut each one first if you like.
Between files: Straight on, with 0.5, 1, 2 s of silence, or crossfaded over 0.5, 1, 2, 4 s: the end of one fades out as the next fades in, at equal power so the loudness does not dip. A crossfade is never longer than half of either file.
Matching files: Files of different rates and channels are made the same (the first file's rate unless you choose one, and stereo when any is stereo). Choose Normalize loudness and each file is measured and brought to the target by itself, so they come out equally loud; one limiter keeps the peaks of the whole under the ceiling.
Chapters: An MP3 or M4A gets a chapter for each file, named after it: ID3 chapters in an MP3, which most players and podcast apps read; a Nero chapter list in an M4A, which VLC, FFmpeg and foobar2000 read. Apple's own apps read chapters of another kind, which is not written.
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