Audio often arrives in pieces: a podcast recorded in segments, an audiobook split into chapters, a set of voice memos that belong together, or a voice track and a music bed that should play at the same time. Handling one file is easier than handling ten, and some uses, such as a single upload or a background track, need exactly one.
This tool offers two ways to combine audio. One after another joins the files in the order of the list, like tracks on an album. Play together layers them so they sound at once, like a voice over music. Add the files, choose the method and an output format, and press Convert. The merging happens locally in your browser.
Joining versus mixing audio
Joining, or concatenating, places each file directly after the previous one. The result lasts as long as all the inputs together, and each part sounds as it did, just in sequence. Mixing adds the sound waves of the files together sample by sample, so they are heard simultaneously; the result lasts as long as you choose, from the shortest to the longest track.
Files from different sources rarely share the same technical settings. A phone memo might be mono M4A at 48 kHz, a music file stereo MP3 at 44.1 kHz, and a browser recording WebM with Opus. Before combining them, the tool converts every input to 44.1 kHz stereo, so joins are seamless and nothing plays at the wrong speed or pitch. When mixing, each track keeps its own level rather than being turned down automatically, and a limiter on the combined sound stops the loudest moments, where tracks add up, from distorting.
Typical merges
Podcast segments and audiobook chapters
Put intro, interview and outro, or chapters 1 to 12, into the list in order and join them into one file for publishing or listening without gaps between parts.
Voice over a music bed
Choose Play together and First track as the length, with the voice first, so the music stops when the narration does. Lower the music beforehand with Volume Booster if it is too loud.
Collecting voice memos
Several short recordings of one meeting or idea become a single file that is easier to send, archive or transcribe.
Order, length and output
Files are combined in the order shown in the queue; once there are two or more they are numbered and can be dragged into place. Length of a mix applies only to Play together: Longest track runs until every file has finished, Shortest track stops when the first one ends, and First track lasts exactly as long as the file at the top of the list.
Output format offers MP3 (the default), WAV, M4A, OGG and FLAC. MP3, M4A and OGG are encoded at 192 kbps, while WAV and FLAC are lossless. The merged file is named after the first file with -merged added, or -mixed for a mix. Processing is done by the site's audio converter, ffmpeg compiled to WebAssembly, which downloads once (about 31 MB). Each file can be up to 500 MB; joining many long files needs plenty of memory, so a desktop browser is the better choice for hours of material.
How to use this tool
- Drop two or more MP3, WAV, OGG, M4A, AAC, FLAC or WebM files on the box above, or click it to choose them.
- Drag the files into the right order.
- Under How to merge, choose One after another or Play together; for a mix, choose the Length of a mix.
- Choose an Output format, press Convert and download the merged file.
Limitations
- There are no crossfades or gaps between joined files; each one starts the moment the previous one ends.
- In a mix all tracks start together at the beginning. To start one later, add silence to it in an audio editor first.
- Volumes are not adjusted per track. Use Volume Booster or Normalize Audio on individual files before merging.
- Everything is converted to 44.1 kHz stereo, so high-resolution sources are not kept at their original sample rate.