As you can see on the official Download Center, KeePass 2.28 is fully compatible with Windows 98, Windows 98SE, Windows ME, Windows 2000, Windows XP, Windows 2003, Windows Vista, Windows 7, Windows 8, Linux, Mac OS X, BSD, and so on. However, in order to install it on Mac or Linux platforms, you will need to download and install Mono (Mac version and Linux version). This is an open source implementation of Microsoft's .NET Framework. You can find all the necessary instructions to install KeePass on the official web page.
