Add to Calendar Date Augmenter
This module adds "add to calendar" links for events without requiring external libraries. It integrates with other formatters, allowing you to add these links to existing date displays, and can handle recurring events when used with the Smart Date module.
This module provides links to add an event to a calendar, similar to Add to Cal or Add To Calendar Button. Unlike those modules, this one has no external dependencies or libraries it relies on.
Another key difference is that this module leverages the Date Augmenter API to provide a plugin that will add these links to another formatter, instead of forcing you to choose a formatter that only adds add to calendar links. So you can use a feature-rich formatter (providing it also supports this API) and add the links to its output.
Because the Smart Date module supports the Date Augmenter API as well as recurring dates, using this combination allows your site to provide links that will add the entire recurring series to a calendar.