How to merge MP3 and WAV audio files in your browser

1. Add the MP3, WAV, or other audio files

Open Audio Cutter & Joiner and choose one or more files to combine. On desktop, you can also add them by drag and drop.

Inputs can include MP3, M4A/AAC, WAV, OGG, Opus, WebM, and other formats the browser and operating system can decode.

The source files do not need to use the same format. MP3 and WAV, for example, can share the same sequence when the browser can decode both.

2. Trim unwanted beginnings and endings on the waveform

Use the waveform only when a clip has long silence, handling noise, or unwanted material at the beginning or end. For a straightforward two-file join, you can skip this step.

Select the clip and set its used start and end positions with the waveform handles or time fields. The source file itself is not modified.

3. Split a clip to remove an unwanted section in the middle

When unwanted material is in the middle, move the playhead to its boundary and split the clip. Split again when needed, then delete only the unwanted section.

The same approach is useful when you want to keep several separate sections from one long recording.

4. Arrange clips in the final playback order

Arrange the clips in the order you actually want them to play. Drag on desktop, or use the move buttons when that is easier on mobile or with a keyboard.

When there are many files, deciding the final order first makes the rest of the edit easier. Filename or recording-number order does not have to match the finished sequence.

5. Preview the full sequence and clip boundaries

Use the full-sequence preview to check the order before export. If you do not need to replay everything, use the boundary preview to listen only around adjacent clip transitions.

Long silence at the end of one clip, handling noise at the start of the next, or an over-trimmed first syllable is often easier to catch at the boundary.

6. Choose MP3, WAV, or M4A for the output

Choose MP3 when smaller files and easy sharing matter, or WAV when you need uncompressed PCM output. MP3 supports 128 / 192 / 256 / 320 kbps, while WAV is 16-bit PCM.

M4A/AAC is available only when the browser supports AAC encoding through WebCodecs. If M4A is unavailable, use MP3 or WAV.

Current output is 44.1 kHz stereo regardless of the source format.

• MP3: smaller and convenient for sharing; 128 / 192 / 256 / 320 kbps
• WAV: 16-bit PCM; usually much larger
• M4A/AAC: supported browsers only; 128 / 192 / 256 / 320 kbps

This is different from lossless MP3 bitstream concatenation

Audio Cutter & Joiner decodes the source audio for editing and renders the finished sequence as 44.1 kHz stereo. Choosing MP3 encodes the result at the selected bitrate.

This is therefore different from losslessly concatenating the original MP3 bitstreams without re-encoding. It is intended for practical editing such as trimming, splitting, mixed source formats, ordering, and transition checking.

Long recordings still depend on browser memory

Long or high-bitrate recordings can use substantial browser memory during waveform analysis and export. Several long recordings may work on a desktop but feel heavy or fail on a phone.

If processing is too heavy, reduce the number of files, shorten the material first, or use a desktop browser.

Tips and limitations

• For a simple two-file join, add → check the order → preview → save is enough. Use the waveform only when silence or unwanted material needs trimming.
• If M4A/AAC is unavailable, the browser does not provide the required AAC encoding path; choose MP3 or WAV instead.
• To join audio taken from videos, first create the audio files with Video Audio Extractor, then add them here.