LogKext is the only kernel-based freeware keylogger for Mac OS X. LogKext is a freeware opensource keylogger for OS X that hooks into the kernel to bypass userspace security measures.

Control and usage of logKext is through logKextClient. LogKextClient runs through the Mac OS X Terminal. Don't worry, it's not as bad as it sounds.

Simply install the package and logKext will begin running and logging all keystrokes.
A logKext help HTML file will be installed in your root directory and opened after installation.

There are two versions available, depending on your version of Mac OS X.

NOTE: logKext is released under the Apache License 2.0.