BYTETOOLS

Merge Audio Files (Joiner)

Merge multiple audio files into one MP3 online for free. Join songs and voice notes in order, with optional crossfade — everything stays in your browser.

Drop audio files here or click to browseAdd up to 10 files. They are merged locally and never uploaded.

What is the Merge Audio Files (Joiner)?

The ByteTools Audio Merger joins two or more audio files into a single MP3, in exactly the order you choose.

  • Joins any mix of formats — MP3, WAV, M4A, FLAC, OGG and more
  • Automatic resampling so mismatched files still merge
  • Optional crossfade between clips (0–10 seconds)
  • Drag-free reordering with simple up/down controls
  • 100% local — audio is never uploaded
  • High-quality LAME MP3 output with built-in preview

How to use the Merge Audio Files (Joiner)

  1. 1

    Drop two or more audio files onto the box, or click to browse.

  2. 2

    Reorder the list with the arrow buttons until the clips are in the right sequence.

  3. 3

    Optionally set a crossfade length in seconds to blend the transitions.

  4. 4

    Click Merge Audio and wait for the in-browser engine to finish.

  5. 5

    Preview the joined track and download the MP3.

About the Merge Audio Files (Joiner)

The ByteTools Audio Merger joins two or more audio files into a single MP3, in exactly the order you choose. Drop in MP3s, WAVs, M4As or a mix of formats — every clip is resampled to a common format first, so files with different sample rates or channel counts still join cleanly.

It is built for podcasters stitching segments together, musicians combining takes, and anyone who wants to turn a folder of voice notes into one continuous file. An optional crossfade blends each transition smoothly instead of cutting hard from one clip to the next.

Everything runs entirely in your browser using a WebAssembly build of ffmpeg. Your audio never leaves your device — no uploads, no server, no account — so private recordings stay completely private.

Frequently asked questions

Can I merge audio files with different formats or sample rates?

Yes. Every input is decoded and resampled to the same sample rate and channel layout before joining, so an MP3, a WAV and an M4A can all be merged into one file without errors or speed changes.

How does the crossfade option work?

Instead of cutting straight from one clip to the next, the end of each clip fades out while the start of the next fades in over the number of seconds you choose. Each clip needs to be longer than the crossfade for the blend to work.

Is there a limit on how many files I can join?

You can join up to ten files at once. Because merging happens in your browser's memory, keeping the combined length reasonable (roughly an hour of audio) gives the smoothest experience.

Are my audio files uploaded anywhere?

No. The merge runs entirely in your browser using WebAssembly. Your files are processed on your own device and never sent to a server, which makes the tool safe for private recordings and unreleased music.

What format is the merged file?

The joined audio is exported as a high-quality MP3, which plays on virtually every device and app. If you need a different format afterwards, run the result through one of the ByteTools audio converters.

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