Significantly smaller files.
ALAC is a lossless format that prioritizes fidelity over size. Converting to OPUS introduces modern compression that typically reduces file size by an order of magnitude with no perceptible difference at normal playback or viewing.
WHY CONVERT
01
ALAC is a lossless format that prioritizes fidelity over size. Converting to OPUS introduces modern compression that typically reduces file size by an order of magnitude with no perceptible difference at normal playback or viewing.
02
OPUS is accepted by a wider range of audio players, car stereos, and streaming services than ALAC. The conversion removes a recurring compatibility friction without changing what the file actually contains.
03
OPUS files are typically smaller than their ALAC counterparts, which reduces hosting, transfer, and storage costs at scale. The savings compound when serving the same content to many recipients.
Visit this page on any modern browser — no install, no signup, no plugin.
Drag your ALAC into the drop area, or click to pick one from your device.
Conversion runs entirely in your browser. When it's done, your OPUS file downloads to your device.
QUALITY & FIDELITY
FORMAT SPECS
| ALAC | OPUS | |
|---|---|---|
| Extensions | .m4a .caf | .opus |
| MIME types | audio/alac | audio/opus |
| Introduced | 2004 | 2012 |
| Maintainer | Apple | IETF |
| Magic # | — | — |
| Spec | View spec ↗ | View spec ↗ |
COMPATIBILITY
| Platform | Windows | macOS | iOS | Android | Chrome | Firefox | Safari | Edge |
|---|---|---|---|---|---|---|---|---|
| OPUS | App | App | Native | Native | Native | Native | Native | Native |
Why LocalConvert
| Category | LocalConvert | Cloud converters |
|---|---|---|
| PRIVACY | Files never leave your device. The whole pipeline runs in your browser via WebAssembly. | Files travel to a remote server, sit in queue storage, and may be retained for analytics or moderation. |
| COST | Free, no signup, no daily quotas. | Often free for small files; paid tiers for batch / large / commercial use. |
| LIMITS | Limited only by your device's memory and CPU. Uncompressed WAV stems handled comfortably on desktop. | Typical 100 MB to 1 GB per-file caps, plus rate limits. |
Apple's lossless audio format inside an M4A container.
Typical uses
Apple Music lossless, iTunes lossless libraries.
A modern low-latency lossy codec excellent for speech and music across all bitrates.
Typical uses
VoIP, podcasts, real-time streaming.
Yes. LocalConvert is completely free, with no signup and no per-file or per-day limits.
No. ALAC to OPUS conversion happens entirely inside your browser using WebAssembly — your file never leaves your device.
There's no fixed cap — the practical limit is your device's available memory. Very large files may take longer or fail on low-RAM devices.
Yes — once the page has loaded, ALAC to OPUS conversion works without an internet connection. Re-open the page once to cache it.
LocalConvert uses the industry-standard tools (FFmpeg, ImageMagick, Pandoc) — quality matches what professionals use on the command line. Lossy formats will still lose some quality on each re-encode.
Last verified:
ALAC to OPUS is processed in your browser with WebAssembly. No upload, no tracking, no limits. Your file never leaves your device.