Free tool
Audio joiner
This audio joiner merges audio files into one, even when they’re in different formats: an M4A, an MP3 and a WAV join as easily as three of a kind. Put them in order, choose straight on, a pause or a crossfade between them, and save one MP3 or WAV.
- Free
- Mix M4A, MP3, WAV and more
- Nothing is uploaded
Drop your audio files here, or Choose your audio files
MP3, M4A, WAV, FLAC, OGG, AAC, or the sound of an MP4, MOV or WebM video, up to 1 GB and 2 hours each. Everything happens in your browser; nothing is uploaded.
MP3 encoding by LAME, open-source software.
Joining the parts of a recorded call? NoteOwl imports one recording at a time, so a joined file gives you one transcript of the whole call on your Mac, with each speaker labelled.
How it works
How do you merge audio files into one?
Add all the files at once, or a few at a time with Add more files. Reorder them by dragging the handle at the left of each row, or with the arrows. Choose what goes between them, press Join audio files and download the result.
- 1
Add the files
Choose several together. Each row shows the file’s length, format, sample rate and channels, and has a Play button.
- 2
Set the order
Drag a row by its handle, or use the up and down arrows. The top file plays first. Remove any you don’t need.
- 3
Join and save
Straight on for parts of one recording, a pause between separate takes, a crossfade for music. Then download the joined file.
Can you combine audio files in different formats?
Yes. Each file is decoded in the page, brought to one sample rate and channel layout, and written out as one new file, so a phone’s M4A, a podcast MP3 and a recorder’s WAV join without converting any of them first. FLAC, OGG and the sound of videos work too.
The joined file takes the highest sample rate among your files, up to 48 kHz, so none of them is made duller to match the others. Joining a 48 kHz M4A, a 44.1 kHz MP3 and a 16 kHz WAV gave a 48 kHz file of 3:30, the three lengths added up.
Should there be a pause or a crossfade between files?
It depends on what the files are. Parts of one recording should run straight on. Separate voice memos or takes read better with a short pause. Songs or music beds blend with a crossfade, where one fades out as the next fades in over the same seconds.
- Parts of one call or lecture
- ChooseStraight on
- Length of the resultThe lengths added up
- Separate voice memos or interview answers
- Choose1 s or 2 s pause
- Length of the resultOne or two seconds longer per join
- Songs, intros and music beds
- Choose2 s or 5 s crossfade
- Length of the resultShorter by the crossfade, per join
| Your files | Choose | Length of the result |
|---|---|---|
| Parts of one call or lecture | Straight on | The lengths added up |
| Separate voice memos or interview answers | 1 s or 2 s pause | One or two seconds longer per join |
| Songs, intros and music beds | 2 s or 5 s crossfade | Shorter by the crossfade, per join |
How do you change the order of the files?
Drag a row by the dotted handle at its left and drop it where it belongs, or use the arrows at its right, which also work from the keyboard. Files picked together arrive in your file picker’s order, usually by name, so numbered names save a step.
Should the joined file be an MP3 or a WAV?
MP3 to send or keep it: at 192 kbps it takes about 1.4 MB a minute. WAV for an editor or a system that asks for WAV: a 48 kHz stereo WAV takes eight times the space of a 192 kbps MP3, with no second round of compression.
Why join the parts of a recorded call before transcribing it?
To get one transcript of the whole conversation. NoteOwl imports one recording at a time and transcribes it on your Mac with each speaker labelled, so a joined file gives one transcript of the whole call.
For calls still to come, NoteOwl records the call itself, with no bot joining.
FAQ
Questions about joining audio files
Are my files uploaded to be joined?
No. Every file stays on your device: the audio joiner decodes them, joins them and writes the result inside this browser tab. Joining three parts of a call caused no network requests at all, and there is no sign-up.
How many files can I join?
As many as you like, each up to 2 hours and 1 GB. The joined file is built in the browser’s memory, so very long joins are easiest as MP3, about an eighth the size of a stereo WAV.
What sample rate does the joined file have?
The highest among the files you join, up to 48 kHz. The others are resampled to match with a filter that keeps them clean. A file with one channel is placed on both sides if any other file is stereo.
How long does joining take?
Seconds for most files. Three parts of a call, three and a half minutes in all, were joined into one MP3 in about three seconds in Chrome and in Safari’s engine.
Can I join MP3 files without re-encoding them?
This joiner always writes a new file, so it can mix formats and add pauses and crossfades. When every file is an MP3 with the same sample rate and channels, NoteOwl’s MP3 joiner can join them frame by frame with no re-encoding at all.
Can I join audio files on my phone?
Yes. Choose the files, use the arrows to set the order, which is easier than dragging on a small screen, and join them. The result downloads like any file.
Keep exploring
More audio editing tools
- MP3 joinerJoin MP3 files into one in your browser, frame by frame with no re-encoding when they match, in the order you set
- Audio compressorMake any audio file smaller in your browser: pick a quality or a size to fit (such as 25 MB for email) and see the size before and after
- MP3 compressorShrink an MP3 by re-encoding it at a lower bitrate in your browser, with the size before and after; only settings that make it smaller are offered
- WAV compressorMake a WAV smaller in your browser: lossless FLAC, a smaller WAV (lower sample rate, mono, 16-bit) or MP3, with the size before and after
Related
- Meeting recording to textMeeting transcription free in your browser: drop in a Zoom, Teams, Google Meet or Webex recording and get a transcript with times; only the sound is sent, nothing is stored
- AI meeting notes without a botHow NoteOwl records calls from your Mac with no bot joining, and what you get when the call ends
- Speaker recognitionTranscripts that say who said what: speakers separated automatically, and a voice named once is recognised in later meetings, on your Mac
One transcript for the whole call, on your Mac
Free to download. Runs entirely on your Mac.
macOS 26 or later · Apple Silicon (M1 or newer) · 16 GB memory minimum, 24 GB recommended
About NoteOwl
NoteOwl is private AI meeting notes and memory for the Mac. It captures meetings without a bot joining the call, labels every speaker, writes summaries and action items, and builds a memory of every conversation that you can chat with — fully offline, because the speech recognition and the AI run on the Mac itself. Dictation into any app is free; Pro is a one-time purchase.
NoteOwl pricing: what’s free and what Pro adds
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