Downloading AppleJack 1.7 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The following version: 1.6 is the most frequently downloaded one by the program users. The application lies within System Tools, more precisely System Optimization. This free Mac app is a product of Kristofer Widholm, The Apotek.
From the developer:
AppleJack is a user friendly troubleshooting assistant for Mac OS X. With AppleJack you can troubleshoot a computer even if you can't load the GUI, or don't have a startup CD handy. AppleJack runs in Single User Mode and is menu-based for ease of use.
Using AppleJack, you can repair your disk, repair permissions, validate the system's preference files, and get rid of possibly corrupted cache files.
You may want to check out more Mac applications, such as Dock Delight, Snow Checker or SBSystemPrefs, which might be similar to AppleJack.