[12] The FDK AAC encoder employs a more aggressive default low-pass filter than is used in other codecs.

The media frameworks FFmpeg and Libav support audio encoding through libfdk-aac.

[20][21] Debian considers the FDK AAC license non-free because it prohibits people from charging a fee for distributing the library, which runs counter to the "No Discrimination Against Fields of Endeavor" rule in Debian Free Software Guidelines.

However, Fedora states that this will not affect the fdk-aac-free package, which enables only the commonly used "Low Complexity AAC" profile, which is what most people use.

[24] The FSF also considers it to be free, though discourages its use due to the explicit lack of a patent grant.