Proton Calendar vs Tuta Calendar

Proton Calendar is a calendar service for managing events, invitations, and recurring schedules on Android and iOS. Event titles, descriptions, locations, and invited people are protected with end-to-end or zero-knowledge encryption. A free Proton account costs nothing and allows up to 3 calendars. Paid Proton Mail plans allow up to 25 calendars, with calendar sharing by link to other calendar services on the web. Users can send invitations and add events from Proton Mail; appointment scheduling updates availability and adds confirmed meetings. The service supports scheduling links and video meetings, and notifications can arrive through desktop browsers or mobile devices. Calendar import and export are available on paid plans. Subscriptions purchased through proton.me renew automatically, and users can switch plans at any time; upgrades receive prorated credit. Proton is incorporated and headquartered in Switzerland and follows Swiss privacy laws.

Tuta Calendar organizes appointments, business meetings, and repeating tasks across Android, iOS, Linux, macOS, web, and Windows. It supports shared calendars with read-only, read-and-write, or write-and-manage-sharing access. Calendar events, invitations, sharing, and push reminders are described as end-to-end encrypted. Users can send and receive invitations, including password-protected encrypted invitations to external users. Imported calendars sync automatically across devices, while the listed calendar sync type is one-way. Tuta says reminders are hidden from the phone operating system and can arrive offline. The calendar is integrated with Tuta email and contacts. Security features include two-factor authentication; Tuta also describes its clients as open source and its calendar as using zero-knowledge architecture. The Free plan includes one calendar. Revolutionary costs €3 a month, billed monthly, and Legend costs €8 a month, billed monthly; both include unlimited calendars. Tuta is made by Tutao GmbH, based in Hannover, Germany, and founded in 2011.