Add your AAC file
Drop one or more .aac files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
AAC to ALAC
Re-encoding .aac audio as .alac changes how the sound is compressed and which players will accept it. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop AAC files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting AAC audio to Apple Lossless audio
Re-encoding .aac audio as .alac changes how the sound is compressed and which players will accept it. An .aac file holds raw Advanced Audio Coding data, usually as an ADTS stream. AAC was designed as MP3's successor and delivers audibly better quality at the same bitrate, though the bare .aac extension is rarer than AAC audio traveling inside .m4a or .mp4 files.
ALAC, the Apple Lossless Audio Codec, compresses music with zero quality sacrifice, and the .alac extension is occasionally used to label such files explicitly even though the codec normally travels inside an .m4a container. Decoding reproduces the original samples exactly, making it Apple's counterpart to FLAC. For this route the practical draw is native on every Apple platform from iOS to HomePod and mathematically lossless reconstruction — balanced against compresses slightly worse than FLAC on average, which is worth knowing before you commit a large batch.
Why convert AAC to ALAC?
The practical trigger for this conversion is usually a mismatch: with .aac, raw ADTS files handle tags and cover art poorly. Switching to .alac buys you native on every Apple platform from iOS to HomePod, which is why it is the better fit for building a lossless library that syncs cleanly to iPhones and the Music app. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
AAC vs ALAC at a glance
| Aspect | AAC audio (.aac) | Apple Lossless audio (.alac) |
|---|---|---|
| Format type | Lossy — discards detail it judges invisible to shrink files | Lossless — every pixel or sample is preserved exactly |
| How it stores data | a pure MDCT transform codec, free of the hybrid filterbank compromise that limited MP3 | linear-prediction compression conceptually similar to FLAC, typically reaching 40 to 60 percent of PCM size |
| Strongest at | receiving the audio track copied out of MP4 video without re-encoding | building a lossless library that syncs cleanly to iPhones and the Music app |
| Weak spot | raw ADTS files handle tags and cover art poorly | compresses slightly worse than FLAC on average |
| Metadata | no standard tag container exists for raw ADTS streams; ID3 tags are sometimes prepended but poorly supported, so wrapping in .m4a is the reliable way to tag AAC | inherits the full iTunes metadata atom set from its MPEG-4 container, including artwork, composer, and grouping fields |
Pick ALAC as the output
Select .alac in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if ALAC is selectable, the route is real and validated.
Convert on your device
Press Convert. The transcode runs on an FFmpeg engine compiled to WebAssembly, so the audio never leaves your device.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid ALAC file. Outputs keep the original filename with the .alac extension.
AAC to ALAC questions, answered
Will converting AAC to ALAC lose quality?
No new loss is introduced — since aac is lossy-oriented and alac is lossless-oriented, everything the .aac file still contains is carried over exactly. What was already discarded by the original lossy encode cannot be recovered, though; converting to .alac does not "restore" quality.
Is it private to convert AAC files here?
Yes — the .aac file is processed inside your browser tab and never uploaded. The transcode runs on an FFmpeg engine compiled to WebAssembly, so the audio never leaves your device. Close the tab and the file is gone from memory.
Where will the ALAC file work?
Every Apple device and application plays ALAC natively, and cross-platform players such as VLC and foobar2000 handle it on Windows, Linux, and Android. Outside the Apple world support varies by player, which is why cross-platform archives still tend to favor FLAC.
Will the ALAC file be bigger or smaller than my AAC?
Larger, sometimes much larger. A lossless .alac must store every pixel or sample the decoder produced, without the perceptual shortcuts .aac used. Use this route for editing headroom, not for saving space.
What happens to the metadata in my AAC file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, no standard tag container exists for raw ADTS streams; ID3 tags are sometimes prepended but poorly supported, so wrapping in .m4a is the reliable way to tag AAC; none of it is transmitted anywhere because the file never leaves your browser.
Can I convert ALAC back to AAC?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .aac → .alac → .aac is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.