KeePass features a plugin framework. Plugins can provide additional functionality, like support of more file formats for import/export, network functionalities, backup features, etc.
You can download the latest KeePass plugins (and their source code) from http://keepass.info/plugins.html.
Plugin Installation and Uninstallation
If the plugin doesn't provide explicit instructions how to install it, follow these steps:
In short, to "install" a plugin you simply need to unpack it somewhere into the 'Plugins' folder.
To "uninstall" a plugin, delete the plugin files.
What about the security of plugins? Can't malicious plugins 'inject' themselves into KeePass?
If plugins can register themselves (i.e. have write access to the KeePass directory), they could also just replace the whole KeePass.exe. It's rather a problem of file access rights, not the plugin system.
If you worry about this, install KeePass as administrator into the program files directory (which is the default, typically in a folder in 'C:\Program Files (x86)'). Afterwards, run KeePass and other applications only as normal user (without administrator privileges).
This solves the problem above. As the KeePass directory is write-protected for normal users, no other program can copy files into it. KeePass requires the plugins to be in the application directory. Therefore, plugins cannot inject themselves anymore.
If you use the portable package of KeePass or installed it into a different directory, you need to adjust the directory permissions yourself.
PLGX plugins are compiled and stored in a plugin cache directory on the user's system. This cache highly improves the startup performance of KeePass. Old files are normally deleted from the cache automatically (this can be disabled in the plugins dialog).
By default, the plugin cache is located in the user's application data
directory. However, this can be overridden using the
Do not relocate the plugin cache into the 'Plugins' folder of the KeePass application directory, because this can result in a severe performance degradation.