Free Audio Converter for Mac & Windows

Transcription & diarization

Neural noise reduction, quiet speakers lifted, one fixed gain, and 16 kHz mono. What Whisper and pyannote want.

Session recordings headed to transcription or speaker separation

Podcast / listenable

Neural noise reduction, gentle compression, and loudness normalization to podcast levels (−16 LUFS) at 48 kHz stereo.

Recordings people will listen to, not just transcribe

Light touch: normalize only

High-pass filter and loudness normalization. No denoiser.

Clean recordings that only need even levels

None: just convert

Skip cleanup and only change the file format.

When the source is already how you want it

WAV to MP3

Handheld recorders and audio interfaces write big WAV files. MP3 cuts the size by roughly ten times, which matters when you are uploading or emailing a long recording.

M4A to MP3

Voice Memos on iPhone and Mac saves M4A. MP3 is the safer choice when you need a file that opens in older software without complaint.

FLAC to MP3

FLAC keeps every bit of the original, at a size most tools would rather not deal with. MP3 is the practical copy to hand around.

MP3 to WAV

Editing suites and transcription tools often want uncompressed audio. WAV gives them raw 16-bit PCM to work with.

WMA to MP3

WMA is a dead end outside older Windows software. MP3 plays anywhere, so this is usually a rescue job on an old archive.

Audio to Opus

Opus fits hours of speech into very little space. It is the right pick for talk-heavy recordings you want to keep but rarely replay.

Is this audio converter really free?

Yes. Audio Converter is a free desktop app for Mac and Windows, with no account, no subscription, and no cap on how many files you convert. Version 0.2 adds speech cleanup (noise reduction, speaker leveling, and loudness normalization) on top of format conversion.

Do my audio files get uploaded anywhere?

No. Audio Converter does cleanup and conversion on your computer using a bundled ffmpeg engine, so your files never leave your device or touch a server. That also means there is no upload wait and no file-size cap imposed by a web service.

Which audio formats can it convert to?

Audio Converter writes MP3, WAV, FLAC, OGG, Opus, M4A, AAC, WMA, AIFF. You pick one output format per batch from the "Convert to" menu, and every file in the queue is converted to it.

Which audio files can it open?

Audio Converter accepts MP3, WAV, FLAC, OGG, Opus, M4A, AAC, WMA, AIFF, AIF files. Anything outside that list is ignored when you drop it in, so if a file does not appear in the queue, its format is not supported yet.

Can it extract audio from a video file?

Not currently. Audio Converter only accepts audio files, so video files such as MP4, MOV, and MKV are ignored if you drop them onto the window.

Can it convert several files at once?

Yes. Drag in as many files as you like and they queue up as a list. Clicking "Convert all" works through the queue one file at a time, showing the status of each, so you can start a large batch and leave it running.

Where do the converted files get saved?

Audio Converter saves each converted file in the same folder as the original, under the same name with the new extension. Cleanup adds a " - clean" suffix so a cleaned export never shadows a plain conversion of the same source. Nothing is overwritten: if a file of that name already exists, the new one gets a number added, like "session (1).mp3".

Does it work without an internet connection?

Yes. The conversion engine is bundled inside the app, so once Audio Converter is installed it works fully offline. You only need a connection for the initial download.

Does Audio Converter normalize loudness?

Yes. Every cleanup preset except "just convert" normalizes loudness. The transcription preset applies one fixed gain so speaker differences stay intact for diarization. The podcast and light-touch presets use EBU R128 loudness normalization, defaulting to −16 LUFS, which is the usual podcast target.

Can it reduce background noise and lift quiet speakers?

Yes. The transcription and podcast presets run a neural denoiser (RNNoise) and level quiet speakers without gating them out. Advanced settings also cover a faster spectral denoiser, mains-hum notches, a high-pass filter, gentle compression, and optional click removal. Neural denoise is slower: a four-hour session takes about twelve minutes.

What bitrate does it convert MP3 files at?

MP3 output uses the LAME encoder at variable bitrate quality 2, which averages roughly 190 kbps, high enough that most people cannot tell it from the source. Encoder settings are fixed per format. Cleanup (noise reduction, leveling, loudness) is separate and adjustable from the preset menu and Advanced panel.

Which format should I use for a long recording?

For a multi-hour recording you plan to share or upload, MP3 is the safe default because everything plays it. If size is the main concern and the recording is mostly speech, Opus produces a much smaller file at similar clarity. Use FLAC only when you want to archive a lossless master copy.

Why does macOS or Windows show a security warning when I open it?

The Mac build is signed and notarized by Apple. The first time you open it, macOS may still show the standard "developer cannot be verified" prompt simply because the app came from outside the App Store. Right-click (or Control-click) the app, choose "Open," then "Open" again, or go to System Settings → Privacy & Security and click "Open Anyway." On Windows the installer is not yet signed with a paid certificate, so SmartScreen may warn on first run. Click "More info," then "Run anyway."

Which operating systems are supported?

Apple Silicon Macs (M1 and later), Intel Macs, and 64-bit Windows 10 and 11. Linux builds are not yet available.