Compress audio to smaller MP3 files locally. Free, private, runs in your browser.
100% private — your files and text never leave your browser. All processing happens locally on your device.
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Audio Compressor re-encodes common audio formats to MP3 with the local FFmpeg WebAssembly pipeline. Your audio file is read in the browser, processed locally, and returned as a download.
Bitrate controls most of the size tradeoff. Voice recordings often work well at lower bitrates or mono, while music usually needs a higher bitrate to avoid audible artifacts.
Already-compressed MP3, AAC, OGG, or Opus files can get larger if re-encoded at a higher bitrate. Convertful warns when the compressed MP3 is not smaller than the source.
No. FFmpeg.wasm runs in your browser and writes the compressed MP3 locally.
Bitrate has the biggest effect. Lower bitrates make smaller files, and mono output can reduce voice recordings further.
Yes. Efficient MP3, AAC, OGG, or Opus sources can produce a larger MP3 if the selected bitrate is too high. The tool warns when that happens.
No. DRM-protected or encrypted audio cannot be decoded by the local browser FFmpeg build.
Very long or large audio files can hit memory limits, especially on mobile. Keep originals and try a lower bitrate or shorter clip if export fails.