Merge Audio Files
Join several recordings into one file, in the order you want them.
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or drag them here
MP3, M4A, WAV, FLAC, or OGG
- Takes
- MP3, M4A, AAC, WAV, FLAC, OGG, and Opus, mixed freely — the files being joined do not have to match each other or be the same format. AIFF and WMA are not readable in a browser and will be refused.
- Size
- No cap, and no upload. Files that already agree on sample rate and channel count stream through a few megabytes at a time. One that has to be matched to the rest is decoded whole in memory first — around 40 MB per minute of stereo — which has been run to 48 minutes here without trouble.
Your file never leaves your browser during processing
How it works
To merge audio files, drop them onto this page, drag them into the order you want with the arrows, and save the result as a single MP3 — the files are decoded and joined end to end in your browser, and nothing is uploaded.
Joining audio is not the same operation as joining text files. Two MP3s stuck together byte for byte will often play, but only if they happen to share a sample rate and bitrate, and the result carries a stray header in the middle that confuses players about how long the file is — which is why seek bars go wrong on files assembled that way. This tool decodes each file to raw audio instead, lays the pieces end to end on one timeline, and encodes the whole thing once as a single MP3 with one consistent header.
The files are joined in the order shown, which you control with the arrows. There is no gap inserted between them and no crossfade: the last sample of one file is followed immediately by the first sample of the next, so a recording that ends mid-breath will run straight into whatever comes after it. Trim the ends first if you want the seam to sound deliberate.
Audio files rarely agree with each other. A voice memo is 44.1 kHz mono, a music export is 48 kHz stereo, and a single MP3 track can only carry one sample rate and one channel count. When the files differ, everything is matched to the highest sample rate and the widest channel layout present — upward rather than downward, because resampling the better file down to suit the worse one would throw away detail for no reason. Files already at the target stream straight through without being touched.
Which rate a file actually has is measured by decoding a moment of it, not read off its header, and the difference is not academic. An HE-AAC file — the format most podcast feeds use — states its core rate in the header, typically 22,050 Hz, while its decoder hands back 44,100 Hz audio, because the top half of the spectrum is reconstructed separately. Trusting the header there means resampling audio that is already at the target, which stretches it to twice its length an octave down. The rates shown next to each file in the queue are the decoded ones, so what you see is what will be joined.
All of it runs in your browser: decoding uses the codecs already built into it, the MP3 encoder is a WebAssembly module that loads once before processing starts, and the counter under the tool watches network activity while your files are handled and stays at zero bytes sent.
FAQ
Can I merge files of different formats?
Yes. MP3, M4A, AAC, WAV, FLAC, OGG, and Opus can be mixed freely in one join — each is decoded to raw audio first, so the container they arrived in stops mattering. The output is always MP3. AIFF, AVI, and WMA cannot be read in a browser and are refused.
Does the order matter?
Yes, and it is the order shown in the list, which you can change with the up and down arrows before joining. Files are added in the order you drop them in.
Is there a gap or crossfade between the files?
Neither — the pieces are butted directly against each other. If you want a pause between two tracks, add a file of silence in between; if you want a smooth blend, that needs an audio editor, not a joiner.
Does joining reduce the quality?
It costs one generation. There is no way to join compressed audio without decoding it, so the result is re-encoded at the bitrate you choose. Picking a bitrate at or slightly above the highest of your inputs keeps the loss negligible.
How many files can I join, and how big can they be?
No limit is set on either, and nothing is uploaded, so the ceiling is your own tab's memory. Files that already agree on sample rate and channel count are streamed into the encoder a few megabytes at a time, making a long queue a matter of time rather than memory. A file that has to be converted to match the others is decoded whole first — around 40 MB per minute of stereo — which has been run to a 48-minute file here without trouble.
Are my files uploaded?
No. Every file is read, decoded, and encoded in your browser, and the network counter under the tool stays at zero bytes sent throughout.