Upload a AAC file and get a FLAC back. No signup, no watermark, no limit on how many.
AAC is MP3's designated successor and wins at low bitrates by a clear margin. A bare .aac file is the raw ADTS stream rather than the .m4a container most software expects.
Where you run into it: YouTube and streaming audio tracks, broadcast, anything that came out of a device rather than a music shop.
What it costs you: The naked .aac extension confuses a surprising amount of software, which is the usual reason people convert it.
FLAC compresses losslessly: it typically halves a WAV and gives back bit-for-bit the same audio when decoded. It is free, open, and widely supported outside Apple's world.
Where you run into it: Archived rips, Bandcamp and Qobuz downloads, anyone who keeps a music library they intend to still have in ten years.
What it costs you: Half of enormous is still large, and some hardware — car head units especially — will not touch it.
Worth being clear about: converting AAC to FLAC does not restore anything. What AAC threw away is gone, and wrapping the result in a lossless format simply preserves the damaged version perfectly. The file will get several times larger for no gain in sound. Do it when a tool or a workflow demands FLAC input — many editors and DAWs do — and not in the hope of better audio.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
It does not lose anything further, but it does not recover anything either. FLAC will store your AAC audio perfectly, damage and all. Converting this way for sound quality is the single most common misunderstanding about audio formats.
Considerably larger — usually five to ten times the AAC. A lossless format stores every sample, and it has no way of knowing that some of them were reconstructed from a lossy file.
Yes — FLAC is one of the formats this converter writes, so the reverse page exists at /flac-to-aac/. Remember that going back and forth between two lossy formats degrades the audio a little each time.
The file is uploaded to do the conversion — nothing here runs in your browser — and both your upload and the converted result are deleted the moment the file is sent back. Nothing is stored and nothing is logged beyond the request itself.