Shotwell can be used with plugins, which are companion shared libraries that can add support for new publishing destinations or new slideshow transitions.

To see a list of installed plugins, choose Edit ▸ Preferences, and in the Preferences window, click on the Plugins tab. You'll see a list of currently-installed plugins, each with a checkbox by it, and you may enable or disable each by selecting or deselecting the checkbox by its name.

Full documentation on how to develop new plugins is available at