Do the files have to be the same format?

No. Anything the browser can play can go in, mixed freely — an MP3, a WAV and an M4A join without complaint. They are all decoded to raw audio first, matched to the first file's sample rate, and encoded once at the end.

What does the overlap do?

It fades the end of one recording into the start of the next over the number of seconds you choose, instead of butting them together. Half a second removes the click at a join; two or three seconds is a musical crossfade.

Why does my joined file sound like it changes speed?

It should not — inputs are resampled to match before joining, and the note tells you when that happened. If you hear it anyway, the recordings themselves likely differ in speed, which no joiner can correct.

Is there a limit on how many I can join?

Your device's memory, since every recording is decoded to raw samples while the join runs. Raw audio is roughly ten megabytes per stereo minute, so a few dozen files is comfortable and several hours is not.

Audio Joiner

Put several recordings together into one, in the order you choose.

Everything runs inside your browser. Your files never leave your device.

Drop your files here

.mp3, .wav, .m4a, .aac, .ogg, .oga, .opus, .flac, .webm, .weba · they stay on this device

Ask about Audio Joiner

Questions about what this tool does, which option to pick, or what it can and cannot handle.

This is the one part of the site that uses a server. The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong; the tool itself is not guessing.

About the Audio Joiner

Putting recordings end to end sounds trivial until the files disagree with each other, and files nearly always disagree with each other.

The common failure is sample rate. A voice note from a phone might be 48 kHz, a download 44.1 kHz. Concatenating those two arrays of numbers without doing anything about it produces a file where the second half plays about nine per cent fast — a small enough error that it does not sound broken, just oddly hurried, which is worse. Every input here is resampled to match the first file before anything is joined, and the result panel says when that happened.

Channel counts disagree too. A mono recording appended to a stereo one, laid out naively, ends up entirely in the left channel. Mono inputs are copied to both sides instead.

Then there is the seam. Butted straight together, two clips produce a step at the join — the same click that trimming causes, for the same reason. Setting an overlap crossfades one into the next instead, and the crossfade is equal-power rather than linear. That distinction matters: two linear ramps crossing meet at half amplitude, which is audibly a dip in the middle of every join. The equal-power curve holds the perceived level constant across the overlap, and there is a test that checks the level does not sag there.

Order is the order in the list, and the list can be dragged, because joining is nearly always assembling something in a deliberate sequence — an interview from its segments, a playlist, a set of voice notes into one file that can actually be sent.

Everything happens in the tab. Recordings of meetings and conversations are exactly the material you should not be handing to a website to concatenate for you.

How to use it

1Drop in all the recordings.
2Drag them into the order they should play in.
3Leave the overlap at zero for a clean join, or raise it to fade one into the next.
4Name the output, join, and download one file.

Questions

Do the files have to be the same format?: No. Anything the browser can play can go in, mixed freely — an MP3, a WAV and an M4A join without complaint. They are all decoded to raw audio first, matched to the first file's sample rate, and encoded once at the end.
What does the overlap do?: It fades the end of one recording into the start of the next over the number of seconds you choose, instead of butting them together. Half a second removes the click at a join; two or three seconds is a musical crossfade.
Why does my joined file sound like it changes speed?: It should not — inputs are resampled to match before joining, and the note tells you when that happened. If you hear it anyway, the recordings themselves likely differ in speed, which no joiner can correct.
Is there a limit on how many I can join?: Your device's memory, since every recording is decoded to raw samples while the join runs. Raw audio is roughly ten megabytes per stereo minute, so a few dozen files is comfortable and several hours is not.