Merge Audio
Decode two or more audio files, place them one after another, and download a 16-bit WAV.
🔒 Processed entirely in your browser — nothing you enter here is ever uploaded.
The result appears on this page after you run the tool. Nothing you enter is uploaded.
Result
About this tool
Pick two or more audio files. One file is rejected with Please select at least two audio files. Each file is decoded in the browser with the Web Audio decoder. The buffers are then concatenated. The sample rate of the result is the sample rate of the first file. A later file at a different rate is resampled to that rate by linear interpolation before it is copied. The channel count of the result is the largest channel count among the files, not the first file's count. A stereo file followed by a mono file produces a stereo result. A mono file followed by a stereo file also produces a stereo result, and the mono file is expanded to two channels.
Expansion does not invent silence and it does not mix. For each missing channel, the converter copies the source's last channel. A mono buffer expanded to stereo has the same samples on the left and the right. A stereo buffer joined to a four-channel buffer copies channel 2 into channels 3 and 4 of that stereo section. The sections are then copied end to end. The length of the result is the sum of those resampled lengths, so the duration is the sum of the durations after resampling, not a crossfade and not a mix. There is no overlap control and no gain change.
The joined buffer is written as a WAV with 16-bit samples and the result's channel count and sample rate. The download name is merged-audio.wav. A player on the page points at the same blob. Formats you can decode are the formats that browser can already decode. A file the decoder rejects stops the run. The bytes are not uploaded. Clearing the selection and picking a new set replaces the previous file list. The order of the join is the order of that list. There is no trim, no fade, and no per-file volume. If the first file is 8000 Hz and a later file is 48000 Hz, the later file is resampled down to 8000 Hz, which is a real loss of bandwidth, not a tag rewrite. If you need the higher rate, put a file at that rate first. The channel-count rule is the one that surprises people who expect every file to be forced down to the first file's channel count. This page does the opposite: it widens to the maximum and duplicates the last channel to fill the gap.
Example. Two decoded files are required. The WAV uses the first file's sample rate and the wider file's channel count. A mono section inside a stereo result copies its only channel to both left and right. The download is merged-audio.wav.
Limit. There is no crossfade, trim, or per-file gain. A later file is resampled to the first file's rate. Extra channels are copies of that file's last channel, not silence.
Which sample rate does the WAV use?
The first file's. Every later file is resampled to that rate with linear interpolation, then appended. Put the file whose rate you want to keep in the first position.
What happens to a mono file joined with a stereo file?
The result has two channels, because the channel count is the maximum. The mono section is not dropped to silence on one side. Its single channel is copied to both output channels for the length of that section.
Are the files mixed or placed in order?
Placed in order. The duration is the sum of the resampled lengths. There is no overlap, fade, or level change. One file is not enough. The run stops until a second file is selected.
What file do I download?
merged-audio.wav, 16-bit PCM, with the joined channel count and the first file's sample rate. The player uses that same blob. Decoding still depends on the formats your browser can decode.