How to join audio files into one MP3

Joining puts several recordings end to end in one file, for example interview segments, voice notes from the same meeting, or tracks for a short mix. Sound Trimmer's audio joiner handles up to six MP3 or WAV files in your browser.

Step by step

Open the audio joiner and choose two or more files. You can add more afterwards.
Arrange them with the up and down arrows, and remove any you do not need.
Preview the combined audio from the start.
Choose MP3 or WAV and prepare the download.

Prepare the pieces first

The joiner places recordings directly one after another with no gap and no crossfade. That means any silence at the start or end of each file stays in the result. For a tight result:

Trim each file in the audio cutter first, removing dead air before and after the useful part. See how to remove silence.
Add short fades of about 0.05 seconds to each piece so the joins do not click.
Match the volume. If one recording is much quieter, raise it with the volume changer before joining, so listeners do not have to reach for the volume control.
Export the pieces as WAV while preparing them, so you only encode MP3 once at the end.

Mono, stereo and sample rates

You can mix mono and stereo files. If any file is stereo, the result is stereo, and mono recordings are placed in both channels. Files with different sample rates are converted to one rate by your browser when they are decoded, so they play at the correct speed and pitch.

Limits

The joiner accepts up to six files with a combined size of 60 MB and a total length of five minutes. Processing happens in your browser's memory, so very long projects belong in desktop software. Joining is not mixing: it cannot play two recordings at the same time, such as music under a voice.

Common uses

Combining several voice memos into one file to send or transcribe.
Adding an intro and outro to a short podcast or announcement. See making a podcast intro.
Putting together short sound effects or alerts in a set order.

Reviewed October 2026 · How we write our guides · Suggest a correction