I have a requirement to add a calendar to my Drupal 7 website. Currently the Calendar module has an alpha version. This is a little subjective, but I was wondering if the Calendar module is stable enough for my needs. Are there alternatives?
Well, in my recent experience is not yet ready to production, but it depends on your needs. Maybe most of this is because the "partner" module, date, has lots of issues now. I suggest you test both: Calendar and FullCalendar. The Calendar module is more powerful and flexible, but if you need a simple calendar, FullCalendar is ready to go now.
The Calendar module is being rewritten from scratch, see Calendar 7.x-3.x. There will be no upgrade path.
There also is Bootstrap Calendar. But it doesn't seem to be ready for production yet. At my first simple test I didn't got it going with the default settings.