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ConvertBox

Audio Compressor

Compress MP3, WAV, FLAC, and AAC audio in your browser. Adjust bitrate to shrink size while preserving sound — files up to 100MB, no uploads required.

How to Use

  1. Select an audio file to compress (MP3, WAV, FLAC, or AAC — up to 100MB)
  2. Choose a bitrate: 64–96 kbps for voice and podcasts, 128–192 kbps for music, 256 kbps+ for hi-fi
  3. Click the "Compress" button — everything is processed in your browser, with no upload to a server
  4. Compare the original and compressed sizes to confirm the reduction before downloading
  5. The compressed file downloads automatically once finished
  6. Ideal for fitting email attachment limits, faster sharing, or trimming a podcast before upload

All processing is done in your browser, and files are never sent to a server.

Frequently Asked Questions

128kbps is recommended for most uses. Use 192-256kbps for music and 64-96kbps for voice recordings.
At 128kbps and above, the difference is barely noticeable for most listeners.
Yes, you can compress audio from MP3, WAV, FLAC, and other common formats.
If compression fails: (1) use a file under 100MB, (2) try a different bitrate setting, (3) convert the audio to MP3 first, (4) refresh the page and retry.
No. Compression runs locally via FFmpeg.wasm — the file is never transmitted.
Speech compresses to 64 kbps cleanly; music typically stays transparent at 128–192 kbps. Use 320 kbps for archival.
No. Output stays in standard MP3/AAC/Opus containers, supported by every modern player and browser.
No. All operations are processed entirely inside your browser's local sandbox using client-side APIs (like WebAssembly, pdf-lib, or HTML5 Canvas). Your files and data never leave your device.
The tool is completely free with no usage limits. However, since processing occurs in your browser's memory, we recommend keeping file sizes under 50MB (especially for heavy files like PDFs or videos) to ensure stability.
No. All tools on ConvertBox are 100% free. We do not insert watermarks, limit features, or require any registration or payment.
Yes. Once the page and its local library dependencies are loaded in your browser, the conversion logic runs completely offline without needing an active internet connection.

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