A user-friendly, open-source tool that automatically ejects and mounts USB and USB 3 drives when your device goes to sleep or wakes up. You can also create custom mount/unmount scripts with this application. It conveniently resides in your menu bar for quick access and hassle-free operation.
SafeSleepUSB 1.1 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The actual developer of this free Mac application is Shilohhh.
From the developer:
SafeSleepUSB is a neat, open source application that allows you to auto eject and mount USB and USB 3 drives at sleep and wake modes. With this application you can write mount/unmount scripts. The application lives in your menu bar and is very easy-to-use.