Merge MP3 files
Join songs, audiobook chapters or recordings into one MP3, in the order you choose.
- Nothing is uploaded
- Works offline after first use
- Open source
- No watermark · limit is your device’s memory; phones hold less
Combine MP3 files into a single MP3 in your browser: songs, audiobook chapters or voice notes, in any order. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The size limit is your device’s memory, and phones hold less; give the page a short while after your first run to save itself for offline use, and then it works offline.
Done
Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
Audiobooks and lectures often arrive as dozens of short MP3 chapters, and a playlist or a mix is easier to share as one file. This page joins MP3 files end to end into a single MP3 that plays in any app, car stereo or phone.
Drop the files in, sort them with the arrows (they keep the order you add them in), and choose whether to add a short pause or a crossfade between tracks. The joined file is written once at the quality you pick, so it plays without gaps or glitches at the joins.
The files are decoded and joined by your browser. Nothing is uploaded, so private recordings stay private and your device’s memory (phones hold less) is the limit on how many you join.
For an audiobook, the order is what usually goes wrong. Files join top to bottom in the order they were added, and a file picker often sorts Chapter 10 before Chapter 2. Check the list before you press Merge MP3 and fix the order with the arrows; naming files 01, 02, 03 before you start avoids it. Leave Between files on Nothing, straight on for chapters. For voice notes or separate talks, 1 or 2 seconds of silence makes each start easy to hear.
Set the MP3 quality to match the files you start with. Chapters at 64 or 128 kbps gain nothing at 320 kbps and only make a larger file; 128 kbps is right for spoken word. Files do not need to match each other: different bitrates and sample rates are all decoded at 44.1 kHz, and a mono chapter is copied to both sides when the others are stereo. The result is saved as merged.mp3, so rename it before adding it to a library.
How it works
- Drop the MP3 files, or tap to pick them. Sort them with the arrows.
- Choose what goes between tracks, and the MP3 quality: 128 kbps suits speech, 192 kbps music.
- Merge and download the single MP3.
In your browser, not on a server
Your browser’s own audio decoders read each file (MP3, AAC in M4A or MP4, Opus or Vorbis, FLAC, WAV) into plain samples at 44.1 kHz in your tab. The sounds are laid end to end, with equal-power crossfades if you chose them, and written once as MP3 by LAME compiled to WebAssembly, or as a 16-bit WAV.
Compared with upload-based tools: Online audio joiners upload every file, cap free use at a few files or a few minutes, and keep the uploads on their servers. Here the files never leave your device, and your device’s memory (phones hold less) is the limit on how many you join.
Verify it yourself. Give the page a short while after your first run to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
Why not just stick the MP3 files together?
Gluing the bytes together (as some command-line tricks do) leaves each file’s tags and encoder padding at the joins, which causes clicks, wrong durations and players that stop after the first track. Decoding and writing one new MP3 avoids all of that.
Will the song titles and cover art be kept?
No. The merged file is a new MP3 without tags; add a title and cover in your music app afterwards if you need them.
How many files can I merge?
As many as your device’s memory holds. A few hours of audio is fine on a laptop; very long merges on a phone may be slow.
How does the crossfade work for a DJ style mix?
With a crossfade, the end of one track overlaps the start of the next, one fading out while the other fades in, so the join is smooth and the mix is shorter than the tracks added up. The 5 second crossfade suits songs; 2 seconds suits short clips. A crossfade never takes more than half of the shorter track, so a brief jingle is not swallowed.
Can I merge MP3s with WAV or M4A files?
Yes. Any file your browser can play can go in the list, including WAV, M4A, FLAC, OGG and the sound of a video. Everything is decoded to the same format before joining, so mixed files work fine. Choose MP3 under Save as for one file that plays everywhere, or WAV if you will edit the result.
Is the file uploaded anywhere?
No. There is no server in this process. The page is a static file and the work is done by code running inside your browser tab. Give the page a short while after your first run to save itself for offline use; then you can turn off Wi-Fi and it still works.
More video and audio tools
Merge audio
Combine songs, voice notes or podcast segments into one file. Done on this device, never uploaded.
Blur faces in video
Faces found and covered frame by frame, on your own device, for children, bystanders and anyone who did not agree to be filmed. Always watch the result before you share it.
Remove silence
Shorter recordings without the dead air, made on your own device. Interviews and lectures stay private.
Transcribe audio to text
Speech to text and subtitles made by an AI model running in this tab. Interviews, lectures and voice notes are never uploaded.
Other conversions
Guides
- How to merge audio filesJoining voice notes, podcast segments or songs end to end is simple once you know the right tool. Here is the desktop way and a private browser way.