What tools/sites do you use for adding multiple calendar options into emails and landing pages? Including iCalendar, Google Calendar, Outlook, Outlook Online, and Yahoo! Calendar.
Have you looked at Agical? It's a tiny, totally free (no paid version, ever) service we created to work around some insufficiencies in Marketo Calendar tokens. You can search old Community posts for more info.
Eventable is a free service that allows you to embed "Add to Calendar" buttons in Marketo emails and landing pages. The buttons work with all calendar types. You can create unlimited events with unlimited calendar adds. Check it out here: https://add.eventable.com/free-add-to-calendar-button
Linking to your own commercial product isn't allowed on the forum, Michelle.