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Calendars by Readdle alternatives · Calendar

Open-source alternatives to Calendars by Readdle

Calendars by Readdle is not described as open source on its own site. 11 of the 75 other calendar and scheduling apps in this directory are open source, according to their own sites.

Calendars by Readdle has a free plan. Paid plans start at $19.99 per year, or $3.99 per month (US App Store in-app purchases). All of them are free or have a free plan.

11 tools · Listings checked up to Oct 9, 2026 · Where the facts come from

How each one differs from Calendars by Readdle

  1. Merkuro Calendar

    Open-source calendar and task app from KDE for Linux

    • Merkuro Calendar is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Merkuro Calendar lists a Linux app.
    • Only Calendars by Readdle lists macOS and iOS apps.
    • Merkuro Calendar is open source, according to its own site.
    Merkuro Calendar pricing and details

  2. Proton Calendar

    End-to-end encrypted calendar from the maker of Proton Mail

    • Proton Calendar starts at $3.99 per month, billed every 12 months ($47.88); $4.99 billed monthly. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Proton Calendar lists a web app.
    • Only Proton Calendar lists Windows, Linux and Android apps.
    • Proton Calendar is open source and end-to-end encrypted, according to its own site.
    Proton Calendar pricing and details

  3. Tuta Calendar

    End-to-end encrypted calendar bundled with Tuta Mail

    • Tuta Calendar starts at €3 per month, paid yearly (€3.60 paid monthly). Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Tuta Calendar lists a web app.
    • Only Tuta Calendar lists Windows, Linux and Android apps.
    • Tuta Calendar is open source and end-to-end encrypted, according to its own site.
    Tuta Calendar pricing and details

  4. Itsycal

    Free, tiny menu bar calendar for the Mac

    • Itsycal is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Calendars by Readdle lists an iOS app.
    • Itsycal is open source, according to its own site.
    • Itsycal also covers menu bar app.
    Itsycal pricing and details

  5. MeetingBar

    Free Mac menu bar app that shows and joins your next meeting

    • MeetingBar is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Calendars by Readdle lists an iOS app.
    • MeetingBar is open source, according to its own site.
    • MeetingBar also covers menu bar app.
    MeetingBar pricing and details

  6. Fossify Calendar

    Open-source Android calendar with no ads, tracking or account

    • Fossify Calendar is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Fossify Calendar lists an Android app.
    • Only Calendars by Readdle lists macOS and iOS apps.
    • Fossify Calendar is open source, according to its own site.
    Fossify Calendar pricing and details

  7. Etar

    Open-source Material Design calendar for Android

    • Etar is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Etar lists an Android app.
    • Only Calendars by Readdle lists macOS and iOS apps.
    • Etar is open source, according to its own site.
    Etar pricing and details

  8. GNOME Calendar

    Free, open-source calendar app for the GNOME desktop on Linux

    • GNOME Calendar is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only GNOME Calendar lists a Linux app.
    • Only Calendars by Readdle lists macOS and iOS apps.
    • GNOME Calendar is open source, according to its own site.
    GNOME Calendar pricing and details

  9. Timeful

    Free, open-source group availability poll with calendar autofill

    • Timeful is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Timeful lists a web app.
    • Only Calendars by Readdle lists macOS and iOS apps.
    • Timeful is open source and self-hostable, according to its own site.
    Timeful pricing and details

  10. Rallly

    Open-source meeting polls for finding a time that suits a group

    • Rallly starts at $6 per seat / month, billed yearly ($10 billed monthly). Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Rallly lists a web app.
    • Only Calendars by Readdle lists macOS and iOS apps.
    • Rallly is open source and self-hostable, according to its own site.
    Rallly pricing and details

  11. Crab Fit

    Free, open-source availability heat map for group events

    • Crab Fit is free. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
    • Only Crab Fit lists a web app.
    • Only Crab Fit lists an Android app.
    • Only Crab Fit lists a browser extension.
    Crab Fit pricing and details

Common questions

Is there an open-source alternative to Calendars by Readdle?

Yes. Merkuro Calendar, Proton Calendar, Tuta Calendar, Itsycal, MeetingBar, Fossify Calendar, Etar, GNOME Calendar and 3 more are open source, according to their own sites.

Is Calendars by Readdle open source?

Calendars by Readdle is not described as open source on its own site. The listing was checked on Oct 5, 2026 against the pages it cites.

When was this checked?

Each listing shows its own date. On this page they run from Oct 5, 2026 to Oct 9, 2026. Vendors change prices and plans without notice, so confirm on their site before you buy.

This page is built from the listings. A tool is here because its listing says so, and the order is how close each is to Calendars by Readdle: the alternatives its listing names first, then the tools that share the most features with it.