About the Audio Joiner
Join several audio files into one: songs into a mix, voice notes into a single message, chapters into a full audiobook, or an intro and outro around a podcast episode. Add the files, put them in order and save one file that plays them back to back.
The files can be in different formats, sample rates and channel counts; they are matched up automatically. Everything runs in your browser, so nothing is uploaded, with up to 20 files and 100 MB in total.
How it works
The audio engine reads each file's details first: its sample rate, whether it is mono or stereo, and its length. Every file is then brought to the sample rate of the first one and to stereo, because a single output file needs one format all the way through.
A mono file, such as most voice notes, is copied to both the left and right sides at its full level, so it sounds as loud as it did on its own. The files are then played one after another, with no gap added and nothing cut off.
The joined file is saved in the format of the first file when it can be written (MP3, M4A, WAV, FLAC or OGG), or as MP3. You can choose another format before joining.
Assumptions and limits
- Files are joined in the order listed; the arrows move a file up or down.
- No crossfade or pause is added between files.
- Up to 20 files and 100 MB in total, since every file is held in memory while joining.
Worked examples
WhatsApp voice notes
Add the voice notes in the order they were sent and save one M4A or MP3 to keep or forward as a single message.
A podcast with an intro
Add the intro jingle, the episode and the outro, in that order, and join them into one MP3.
Different formats together
A 44.1 kHz stereo MP3 followed by a 48 kHz mono WAV joins into one stereo file at 44.1 kHz, with the WAV at the same loudness as before.
How to use the Audio Joiner
- Add two or more files. Any mix of audio formats, up to 20 files.
- Put them in order. Use the arrows to move a file up or down.
- Join and download. One file that plays them back to back.
Frequently asked questions
How do I combine MP3 files into one?
Choose two or more MP3 files on this page, arrange them with the arrows, and press Join audio. The files play one after another in the saved file. It all runs in your browser, so the MP3s are never uploaded.
Can I join files with different formats?
Yes. You can mix MP3, WAV, M4A, OGG, FLAC and the sound of videos. Each file is converted to the first file's sample rate and to stereo before joining, so the result plays smoothly as one file.
Will a mono voice note sound quieter after joining?
No. A mono file is placed on both the left and right channels at its original level. Some joiners lower mono files by 3 dB when making them stereo; this one keeps the level you recorded.
Is there a gap between the files?
No gap is added. Each file starts right after the previous one ends. If a file has silence at its start or end, that silence stays; trim it first with the audio trimmer if you want a tighter join.
How many files can I join?
Up to 20 files, adding up to 100 MB. All of them are held in your device's memory while they are joined, so this limit keeps it working on phones as well as computers.
This tool runs entirely in your browser. What you enter or upload stays on your device and is never sent to our servers.