Alternatives to Proton Calendar

An end-to-end encrypted calendar from Proton, available on the web and on iOS and Android. The listings below can replace it for an important use case. Each note says what changes if you switch.

Replacements

Listings that take over the same core job as Proton Calendar.

  • Google Calendar

    Google's free web calendar for scheduling events, used with a Google account and synced across devices.

    FreeProprietaryWeb

    Google Calendar is free and widely supported by other tools, but events are stored on Google's servers without end-to-end encryption and it requires a Google account.

  • Microsoft Outlook

    Microsoft's email, calendar and contacts app for desktop, mobile and the web.

    FreemiumProprietaryWindowsmacOSAndroidiOSWeb

    Microsoft Outlook combines email, calendar and contacts on desktop, mobile and web within Microsoft 365, but is closed source and tied to Microsoft services instead of encryption.

  • Fastmail

    A paid, privacy-focused email, calendar and contacts service with web and mobile apps.

    PaidProprietaryAndroidiOSWeb

    Fastmail is a paid email, calendar and contacts service with EU or USA data residency and custom domains, but it does not describe end-to-end encrypted events.

  • Fantastical

    A calendar and tasks app with natural language event entry for Mac, Windows and iOS.

    FreemiumProprietaryWindowsmacOSiOS

    Fantastical is a calendar client for Mac, Windows and iOS that merges many calendars with natural language entry, but has no Android version and premium features cost extra.

  • Notion Calendar

    A free calendar app, formerly Cron, that works with Google Calendar and Notion workspaces.

    FreeProprietaryWindowsmacOSAndroidiOS

    Notion Calendar is a free app for Windows, macOS, Android and iOS with scheduling links, but it is built around Google Calendar and Notion rather than encryption.

  • Mailfence

    Encrypted email service from Belgium with OpenPGP support, calendars, contacts and document storage.

    FreemiumProprietaryAndroidiOSWeb

    Mailfence is a Belgian encrypted email service with OpenPGP, calendar, contacts and documents in one account, offering standard IMAP access and a free tier.

  • BusyCal

    A calendar app for Mac, iPhone and iPad with tasks, smart filters and natural language entry.

    PaidProprietarymacOSiOS

    BusyCal is a paid calendar app for Mac, iPhone and iPad that works with iCloud, Google, Exchange and CalDAV, but runs only on Apple platforms.

  • Etar

    An open-source Material Design calendar app for Android.

    FreeOpen sourceAndroid

    Etar is a free GPL-3.0 Android calendar with no proprietary components, whose sync depends on the accounts set up on the phone.

Also worth comparing

These listings name Proton Calendar as their own alternative, so the relationship runs both ways.

  • calcurse

    A text-based calendar and to-do application for the terminal with reminders and scripting options.

    FreeOpen sourceLinuxCommand line

    Proton Calendar moves events into an end-to-end encrypted web and mobile calendar, but it requires a Proton account and has no terminal interface.

  • Vimcal

    A keyboard-driven calendar that combines Google and Outlook calendars and helps share availability across time zones.

    PaidProprietaryWeb

    Proton Calendar end-to-end encrypts event details and includes booking, but requires a Proton account and works best within the Proton ecosystem.

Similar software

Related functionality, not a direct replacement.