ProtonMail is an email service known for being privacy-conscious and encrypting emails. It's popular among people who seek more secure alternatives to Gmail. Proton has expanded its line up services to include encrypted contacts, and now the company is branching out into the calendar game with ProtonCalendar.
The premise of ProtonCalendar is the same as ProtonMail: an encrypted alternative to Google's offering. It uses end-to-end encryption to keep all of your events' information private and secure. That means the event title, description, location, and participants are encrypted on your device before they reach the Proton servers. No third-party (even ProtonMail) can see the details.
ProtonCalendar offers all the basic features you would expect from a calendar service. You can create events, delete events, set reminders, invite others to events, repeat events on a schedule, and so on. Right now, ProtonCalendar is in beta and only available on the web. Eventually, it will come to Android and iOS next year. If you are currently a paid user of ProtonMail, you can try out the calendar beta right now at the link below.
Source: ProtonCalendar Beta