Audio Joiner — Merge MP3 and Audio Files
Join several songs, voice notes or sound clips into one MP3 or WAV in your browser, with an optional gap or crossfade between them. Nothing is uploaded.
How to use
- Drop two or more audio files on the box, or click to choose them.
- Put them in order with the arrows and remove any you do not need.
- Set a gap of silence or a crossfade, and choose MP3 (with a bitrate) or WAV.
- Press Join, listen to the result, and download it.
About this tool
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Add two or more audio files — MP3, WAV, M4A/AAC, FLAC, OGG/Opus, or the sound track of a video — put them in order, and the tool joins them into one file. Choose a gap of silence between clips, or a crossfade in which each clip fades out while the next fades in. The result plays in the page so you can check it, then downloads as MP3 at the bitrate you pick or as an uncompressed 16-bit WAV. Every file is decoded by your browser and nothing is uploaded.
Clips with different sample rates or channel counts are brought to one format first: the highest sample rate among them (capped at 48 kHz, the MP3 maximum) and stereo if any clip is stereo, with mono clips placed in both channels. The crossfade is equal-power, so a steady sound keeps its loudness through the join, and it is limited to half of the shorter clip on either side; with a crossfade set, the gap is ignored. The total length shown before joining follows the same rules.
The tool does not even out loudness: a quiet recording next to a loud song stays quiet. MP3 is lossy, so joining MP3s and saving as MP3 again re-encodes them; choose 192 kbps or more for music, or WAV if you will edit the result further. Very long sets use a lot of memory, so the total is limited to one hour. MP3 encoding uses lamejs, a JavaScript port of the LAME encoder (LGPL), which loads only when you save an MP3.
Frequently asked questions
Are my files uploaded?
No. Each file is decoded by your browser, joined in memory and encoded on this page. Nothing is sent anywhere.
Can I join files of different formats?
Yes. MP3, WAV, M4A/AAC, FLAC and OGG/Opus can be mixed, as can the sound of video files, as long as your browser can decode them. They are converted to one sample rate and channel count before joining.
What is the difference between a gap and a crossfade?
A gap inserts silence between clips. A crossfade overlaps the end of one clip with the start of the next, fading one out while the other fades in, so the join is seamless and the total is shorter.
Will the quality drop?
Saving as MP3 re-encodes the audio, which loses a little quality each time. Use 192–320 kbps for music, or save as WAV for a lossless result.
Why is one part much quieter than the rest?
The tool does not change volume. If your recordings were made at different levels, they keep those levels in the joined file.
Is there a length limit?
The joined file can be up to one hour long. Everything is held in memory as uncompressed audio, which for an hour of stereo is well over a gigabyte.
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