AudioShrink100% in-browser audio compressor

Shrink audio and voice notes before you send them.

Re-encode MP3, WAV, M4A, OGG and WebM at a lower bitrate, right on your device. Handy when your data bundle is nearly gone or the connection is slow.

Your audio is processed locally in your browser and is never uploaded to our server. No accounts, no uploads — the file never leaves this page.

Works offline · Bulk files · ZIP export

Upload and compression workspace

1 · Add audio

up to 10 files
Drag & drop audio here or use the button below — files stay on your device
up to 300 MB each · multiple files OK

Maximum 300 MB per file.

2 · Quality preset

Honest results only. AudioShrink reports the real size of the file it produced. If your browser cannot encode the format you chose, we say so instead of pretending.
Lossy encoding runs in real time, so a 5-minute recording takes about 5 minutes. WAV output is instant.

4 · Your files

0 files

Results

actual sizes measured after encoding

Nothing compressed yet. Add audio and press Compress All.

Frequently asked questions

Four quick answers about privacy, formats, quality and how much you can save.

Q. Is my audio private — does it ever get uploaded?

No. AudioShrink has no backend, no database and no upload code path. Your file is read with the browser's FileReader/File API, decoded by the Web Audio API, re-encoded locally, and handed back to you as a downloadable blob created by your own browser.

Nothing is transmitted to us or to any third party. Turning off your network connection after this page loads and pressing Compress All still works. We only use localStorage for two small preferences: your theme choice and whether you dismissed the cookie notice.

Q. Which input and output formats are supported?

Input: anything your browser can decode — MP3, WAV, M4A/AAC, OGG, WebM, and usually FLAC and OPUS too.

Output: browsers cannot natively encode MP3, so MP3-out is not offered. Instead we re-encode to Opus in WebM (Chrome, Edge, Firefox, Opera), AAC in M4A (Safari on macOS/iOS), or WAV PCM everywhere. The format dropdown only lists what your browser actually supports — unsupported targets are greyed out with an explanation.

Q. How much quality do I lose?

Re-encoding is lossy: samples that a codec judges inaudible are discarded. For spoken voice notes, Maximum Savings (32 kbps mono Opus) still sounds perfectly intelligible over WhatsApp, Telegram or email. Balanced (64 kbps mono) is the safe default, and High Quality (128 kbps stereo) keeps music detail.

Choose WAV if you need an uncompressed, universally playable file — you still save a lot by downsampling to mono and a lower sample rate, but the result is usually larger than an Opus file of the same audio.

Q. How much smaller will my file get?

Roughly (bitrate × duration) ÷ 8. A 10-minute mono WAV at 44.1 kHz is about 50 MB; the same audio at 32 kbps Opus is about 2.4 MB — around 95% saved. A 128 kbps MP3 re-encoded to 64 kbps roughly halves in size.

The estimate shown before you compress is just that — an estimate. The number in your results is the real byte size of the file AudioShrink produced, measured after encoding. If a file comes out bigger than the original (possible when the source is already very compressed), we tell you plainly and suggest a lower preset.

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