I am looking for an alternative for google calendar that allows events to be categorized into different groups (which can be toogled by the users). So for instance that one wants to see only the events for "food" in the upcoming month. The calendar can be public, private team events are not needed. It has to be free as it is for a small non-profit organization.
Any suggestion highly welcome!
EDIT: Should mention that web options are prefered, but the organization has a little website, so hosting is also possible.