What are some alternatives?
When comparing Simple Calendar and CalReply, you can also consider the following products
Google Calendar - Spend less time managing your day & more time enjoying it
Time.ly - Time.ly is a collaborative calendar solution for websites.
Lightning Calendar - Organize your life — it’s about time!
Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
MineTime - MineTime is a free, modern and multi-platform calendar application.
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.