Audio Joiner
An audio joiner for stitching clips into one track: queue them in order, set a crossfade if you want them to blend, then export M4A, WAV, Opus, or FLAC.
Runs entirely in your browser — your files and text never leave your device.
Drag & drop your files here, or
Tracks are merged top to bottom. A crossfade blends each track into the next over the chosen seconds; leave it at 0 to join them back to back.
Working on your device — keep this tab open until it finishes.
How to use
- Drop your clips on the Audio files box, or hit Choose files and pick a batch.
- Check the list that appears: one row per clip, each showing its name and its length, merged top to bottom.
- Wrong order? Drag a row by its grip, the dotted handle at its right edge, and drop it where it belongs.
- Leave Crossfade (s) at 0 for straight cuts, or type something like 1.5 to blend each clip into the next.
- Pick an output format. M4A is preselected; WAV, OPUS, and FLAC are the other three.
- Press Join & download. It stays disabled until at least two clips are in the list.
About this tool
An audio joiner has one job: hand it several clips and get back one file that plays them end to end. Files merge top to bottom in the order the list shows them. Crossfade (s) sits at 0 by default, which gives you hard cuts between clips. Put a number in and each clip fades into the one after it over that many seconds.
Every clip decodes the moment it lands, so each row shows the filename next to its real running time, which is usually enough to spot the stray. Rows move by their grip: press the dotted handle at the end of a row and drag it to where the clip belongs. Remove drops one clip out of the queue without disturbing the rest, and a file the browser cannot decode never enters the list at all; a warning names it instead.
Output starts on M4A, with WAV, OPUS, and FLAC beside it. M4A is the small one that plays about everywhere. WAV and FLAC keep every sample intact for whatever editing comes next. The joined file downloads by itself and also lands in a player on the page. Give the joins a listen before you close the tab.
Three songs, two seams, one mixtape
Take three MP3s at 3:41, 4:05 and 2:54, added in that order, with Crossfade (s) set to 2 and the format left on M4A. Straight addition promises 10:40 of audio. The two seams each swallow their overlap, so the joined file plays 10:36.
Press Join & download and the busy note sits by the button while the clips are written into one buffer and the AAC encode runs. The result lands twice, as a joined.m4a download and as a player on the page. The player has one job: scrub to 3:39 and then 7:42 and decide whether two seconds was the right blend.
Good to know
- Every clip is decoded to raw samples and held in memory while the joined track is assembled, so a queue of hour-long files can run a phone out of room. The output also inherits its sample rate from the first clip in the list. Drop a 48 kHz recording in behind a 44.1 kHz one and that later clip plays back about 8 percent slow.
- A crossfade can only blend audio that exists. Ask for ten seconds of overlap going into a three-second sting and the blend runs three seconds, which is all the sting can give.
Frequently asked questions
Why isn't MP3 in the format list?
MP3 encoding needs a licensed encoder and I don't ship one. M4A is the closest swap: it carries AAC, plays on the same phones and car stereos MP3 does, and at matching quality the file usually comes out smaller.
How long should the crossfade be?
For music, somewhere between half a second and two seconds reads as a deliberate blend. For speech, stay under about 0.3 seconds or the words overlap and turn to mush. The field steps in tenths of a second.
Can I mix formats, an MP3 next to a WAV next to an m4a?
Whatever your browser can decode goes in the same list: MP3, WAV, M4A, OGG, FLAC. Anything that fails to decode gets skipped, and a warning names the file it dropped.
Does joining knock the quality down?
Each clip is decoded to raw samples first, then the whole thing is encoded once at the end. A lossy source picks up one more generation of encoding that way. Pick WAV or FLAC and the final step is lossless, which matters when the joined file is heading into an editor.
Why is the joined track shorter than my clips added together?
Crossfaded stretches play once, not twice. Every seam subtracts its overlap from the running total, so three two-minute clips with two-second fades land at 5:56 rather than 6:00. Set the crossfade back to 0 and the lengths add up exactly.
One clip is mono and the rest are stereo. What comes out?
The join runs at the widest channel count in the queue. A mono voice memo gets its single channel copied into both ears, so it sits dead centre between the stereo songs instead of leaning out of one side.
How many clips can the queue take?
No number is enforced; memory is the real wall. Decoded stereo at 44.1 kHz costs about 21 MB a minute while the join is being built, so an hour of material wants well over a gigabyte of headroom, and a phone taps out long before a desktop does.
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