Wrap your AAC audio in an M4A container, the format Apple devices and iTunes prefer. The conversion runs right in your browser with nothing uploaded.
In “Local” mode your file never leaves your device. No uploads, no server – ideal for sensitive recordings.
Pick “Local” for full privacy or “Server” for very large files and every format.
No sign-up, no queue, no watermark. Choose a file, convert, download.
Virtually not at all. M4A is usually just a different container around the same AAC audio stream, so there's little or no extra quality loss.
AAC is the actual audio format, while M4A is an MP4-based container that commonly holds AAC audio. Apple software tends to prefer M4A.
Yes. M4A is the format iTunes, the Music app and iPhones prefer, and it plays natively without any extra software.
No. By default everything stays in your browser. Only very large files can optionally use the server mode.