Audio Joiner

How to use the Audio Joiner

1. Choose or drag in two or more audio files. You can add more at any time.
2. Put them in order with the ↑ and ↓ buttons (or drag a row by its ☰ handle on a computer). Remove a clip with ✕.
3. Choose what happens between clips: play them back to back, insert a silence gap, or blend them with a crossfade.
4. Leave sample rate and channels on Auto unless you need a specific format.
5. Click Join and create WAV, listen to the result, then download it.

How it works

Each clip is decoded by your browser's built-in audio decoder. Because clips can come from different sources, they may have different sample rates (for example 44,100 Hz from a music file and 48,000 Hz from a phone recording) or channel counts. Before joining, every clip is converted to one common format using the browser's own high-quality resampler (an OfflineAudioContext render), so nothing plays too fast or too slow. A mono clip placed in a stereo result is copied to both speakers.

The clips are then copied one after another into a single buffer. A silence gap inserts that many seconds of digital silence between clips. A crossfade overlaps the end of one clip with the start of the next and blends them with an equal-power curve (the outgoing clip fades as a cosine, the incoming one as a sine), which keeps the perceived volume steady through the change. Each crossfade makes the total shorter by its own length, and it is automatically shortened if a clip is shorter than the crossfade.

Example: joining clips of 30 s, 45 s and 60 s back to back gives 2:15. With a 2-second gap it becomes 2:19, and with a 2-second crossfade it becomes 2:11.

The output is a 16-bit PCM WAV file, which is lossless and plays on practically every device. It is larger than an MP3, at about 10 MB per minute of stereo 44.1 kHz audio.

Frequently asked questions

Can I join files in different formats?
Yes. You can mix MP3, WAV, M4A, OGG and FLAC in one job, as long as your browser can decode each file. They are all converted to the same sample rate and channel count before joining.

How many files can I add?
There is no fixed limit, but every clip is held in memory as raw audio (about 10 MB per stereo minute). Keep the total under roughly 30 minutes on a computer and 10 minutes on a phone.

What is the difference between a gap and a crossfade?
A gap adds silence between clips, which suits separate tracks or spoken segments. A crossfade overlaps and blends the clips so one flows into the next, which suits music mixes.

Why WAV instead of MP3?
WAV is lossless and universal, and it can be created with plain browser code. MP3 encoding would need an encoder library whose license we do not use on this site.

Are my files uploaded?
No. Everything happens in your browser, and the joined file is created on your own device.