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Open Source Google Calendar Alternatives

The best open source alternative to Google Calendar is Etar. If that doesn't suit you, our users have ranked more than 100 alternatives to Google Calendar and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Google Calendar are Calendar Lock PEA, Lightning Calendar, Simple Calendar and Proton Calendar.

Google Calendar alternatives are mainly Calendar Apps but may also be Email Clients or Todo List Managers. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Google Calendar.
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  • FreeProprietary
  • Online
  • Android
  • iPhone
  • Chrome OS
  • Android Tablet
  • iPad
  • Sunbird
  • Google Chrome

With Google Calendar, its easy to keep track of all your lifes important events in one place. You can add events and send...

Learn more about Google Calendar

  1. Etar icon

    Etar

    • FreeOpen Source
    • Android
    • Android Tablet

    Material design open source calendar for Android.

    ⚫︎ LightweightEtar consumes less device resources compared to similar apps.
    ⚫︎ Ad-freeEtar doesn't contain any form of external advertising.
    ⚫︎ Privacy focusedEtar is considered a privacy friendly alternative.
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    Etar vs Google Calendar opinions
    Almost everyone thinks Etar is a great alternative to Google Calendar.
    3rd

    Import and export function is listed but it didnt work for me at all. Worse, on my latest phone I could not even import an ICS file with all my stuff.

    Negative comment ago
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    Open source and works well !!

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    Nice, clean, and to the point calendar!

    Positive comment ago
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    7
  2. Calendar Lock PEA icon

    Calendar Lock PEA

    • FreeOpen Source
    • Mac
    • Windows
    • Linux

    Calendar encryption: View calendars and stores them encrypted on your device or in the cloud.

    ⚫︎ Privacy focusedCalendar Lock PEA is considered a privacy friendly alternative.
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    Calendar Lock PEA vs Google Calendar opinions
    Almost everyone thinks Calendar Lock PEA is a great alternative to Google Calendar.


  3. Lightning Calendar icon

    Lightning Calendar

    • FreeOpen Source
    • Mac
    • Windows
    • Linux
    • Thunderbird
    • SeaMonkey

    Organize your schedule and life’s important events in a calendar that’s fully integrated with your Thunderbird or Seamonkey email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.

    ⚫︎ Ad-freeLightning Calendar doesn't contain any form of external advertising.
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    Lightning Calendar vs Google Calendar opinions
    Most users think Lightning Calendar is a great alternative to Google Calendar.
  4. Simple Calendar icon

    Simple Calendar

    • FreemiumOpen Source
    • Android
    • Android Tablet
    • F-Droid

    A simple calendar with optional CalDAV synchronization. You can easily create recurring events and setup reminders, it can also display week numbers.

    ⚫︎ Dark ModeSimple Calendar supports dark mode for comfortable usage in low light conditions.
    ⚫︎ No TrackingSimple Calendar will not track or use your personal data.
    ⚫︎ Works OfflineSimple Calendar can be used without the need to connect to the internet.
    ⚫︎ CustomizableSimple Calendar is easy to customize with themes or similar features.
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    Simple Calendar vs Google Calendar opinions
    Almost everyone thinks Simple Calendar is a great alternative to Google Calendar.

    Open source, has widgets and is quite configurable

    Positive comment ago
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    1
  5. Proton Calendar icon

    Proton Calendar

    • FreemiumOpen Source
    • Online
    • Android
    • Android Tablet
    • Tor

    Your calendar is a record of your life. Proton Calendar helps keep it private.

    ⚫︎ Privacy focusedProton Calendar is considered a privacy friendly alternative.
    ⚫︎ End-to-End EncryptionProton Calendar has E2E Encryption, for entire or parts of the app.
    ⚫︎ Two-factor AuthenticationProton Calendar supports two-factor authentication (2FA).
    ⚫︎ Dark ModeProton Calendar supports dark mode for comfortable usage in low light conditions.
    ⚫︎ Cloud SyncSync your data (notes, documents, bookmarks, etc.) across your different devices and to the cloud.
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    Proton Calendar vs Google Calendar opinions
    pros, cons and recent comments
    Deivedux

    ProtonCalendar may not be as feature-rich as Google Calendar, but their main focus is protecting user data with end-to-end encryption. The free plan is enough for basic calendar functionality, but paid subscriptions give extra benefits for supporting their business model, as that's their only source of income.

    Positive comment ago
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  6. Nextcloud Calendar icon

    Nextcloud Calendar

    • FreeOpen Source
    • Online
    • Self-Hosted

    The Calendar app is a user interface for Nextcloud's CalDAV server. Easily sync events from various devices with your Nextcloud and edit them online.

    ⚫︎ Cloud SyncSync your data (notes, documents, bookmarks, etc.) across your different devices and to the cloud.
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    Nextcloud Calendar vs Google Calendar opinions
    Most users think Nextcloud Calendar is a great alternative to Google Calendar.

    Free (and open source) alternative. Your data is yours !

    Positive comment ago
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    3
  7. Personal Information Manager (Mail, Contact, Calendar and more).

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  8. Kolab Community icon

    Kolab Community

    • FreemiumOpen Source
    • Linux
    • Online
    • Self-Hosted

    Kolab is entirely Free and Open Source Software (a.k.a. FOSS), and uses Open Standards. We’ll get to why this is important to us, and hope that it is important to you thereafter.

    ⚫︎ Real time collaborationMultiple users can work together in Kolab Community simultaneously.
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    Kolab Community vs Google Calendar opinions
    Some users think Kolab Community is a great alternative to Google Calendar, some don't.
  9. Kalendar icon

    Kalendar

    • FreeOpen Source
    • Linux

    Kalendar is a Kirigami-based calendar application that uses Akonadi. It lets you add, edit and delete events from local and remote accounts of your choice, while keeping changes syncronised across your Plasma desktop or phone.

    ⚫︎ Sync with Google CalendarKalendar can be synchronized with Google Calendar
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  10. Woelkli icon

    Woelkli

    • FreemiumOpen Source
    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad

    woelkli is a service that provides secure cloud storage hosted in Switzerland. Save, view, edit and share your files from anywhere in the world, from any device

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    Woelkli vs Google Calendar opinions
    This alternative is disputed. Woelkli is still a legitimate alternative to Google Calendar, but it might have issues that some users think are important.

    It's a cloud storage service...

    Negative comment ago
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Showing 10 of 27 alternatives