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Best OneCalendar Alternatives in 2026

Updated

20 apps from calendar apps ranked against OneCalendar on the same published basis.

  1. 1
    Mozilla Thunderbird Free plan Open sourceAndroidLinuxMacWin Free9.0
    OneCalendar vs Mozilla Thunderbird
  2. 2
    Microsoft Outlook Calendar Free plan AndroidiOSMacWeb $1.67/mo8.2
    OneCalendar vs Microsoft Outlook Calendar
  3. 3
    Lark Free plan AndroidapiiOSLinuxMac 8.2
    OneCalendar vs Lark
  4. 4
    EGroupware Free trial Open sourceWebLinuxWinMac €21.90/mo8.2
    OneCalendar vs EGroupware
  5. 5
    Proton Calendar Free plan AndroidiOS Free8.0
    OneCalendar vs Proton Calendar
  6. 6
    Teamup Free plan AndroidapiiOSWeb $12/mo8.0
    OneCalendar vs Teamup
  7. 7
    Cozi Free plan AndroidiOSWeb $3.25/mo8.0
    OneCalendar vs Cozi
  8. 8
    Calendar.com Free plan AndroidapiextensioniOSWeb $20/mo8.0
    OneCalendar vs Calendar.com
  9. 9
    TimeFinder Free plan AndroidiOSMacWebWin Free8.0
    OneCalendar vs TimeFinder
  10. 10
    Notion Calendar Free plan AndroidiOS Free7.9
    OneCalendar vs Notion Calendar
  11. 11
    TimeTree Free plan AndroidiOSWeb $3.75/mo7.9
    OneCalendar vs TimeTree
  12. 12
    Doodle Free plan Web $11/mo7.8
    OneCalendar vs Doodle
  13. 13
    Tuta Calendar Free plan AndroidiOS €3/mo7.8
    OneCalendar vs Tuta Calendar
  14. 14
    Reclaim AI Free plan extensionWeb $10/mo7.8
    OneCalendar vs Reclaim AI
  15. 15
    FlowSavvy Free plan AndroidiOSWeb 7.8
    OneCalendar vs FlowSavvy
  16. 16
    Musubi Free plan AndroidiOSself-hostedWeb Free7.8
    OneCalendar vs Musubi
  17. 17
    Samsung Calendar Free plan Android Free7.7
    OneCalendar vs Samsung Calendar
  18. 18
    Fantastical Free plan iOSMacWin Free7.7
    OneCalendar vs Fantastical
  19. 19
    Trevor AI Free plan Web $0.42/mo7.7
    OneCalendar vs Trevor AI
  20. 20
    Calendars by Readdle Free plan iOSMac $1.67/mo7.7
    OneCalendar vs Calendars by Readdle

OneCalendar alternatives compared

#AppScoreFree planFromRuns on
1Mozilla Thunderbird9.0Free planFreeAndroid, Linux, Mac, Windows
2Microsoft Outlook Calendar8.2Free plan$1.67/moAndroid, iOS, Mac, Web
3Lark8.2Free plan—Android, API, iOS, Linux, Mac, Web, Windows
4EGroupware8.2No€21.90/moWeb, Linux, Windows, Mac
5Proton Calendar8.0Free planFreeAndroid, iOS
6Teamup8.0Free plan$12/moAndroid, API, iOS, Web
7Cozi8.0Free plan$3.25/moAndroid, iOS, Web
8Calendar.com8.0Free plan$20/moAndroid, API, Browser, iOS, Web
9TimeFinder8.0Free planFreeAndroid, iOS, Mac, Web, Windows
10Notion Calendar7.9Free planFreeAndroid, iOS
11TimeTree7.9Free plan$3.75/moAndroid, iOS, Web
12Doodle7.8Free plan$11/moWeb
13Tuta Calendar7.8Free plan€3/moAndroid, iOS
14Reclaim AI7.8Free plan$10/moBrowser, Web
15FlowSavvy7.8Free plan—Android, iOS, Web
16Musubi7.8Free planFreeAndroid, iOS, self-hosted, Web
17Samsung Calendar7.7Free planFreeAndroid
18Fantastical7.7Free planFreeiOS, Mac, Windows
19Trevor AI7.7Free plan$0.42/moWeb
20Calendars by Readdle7.7Free plan$1.67/moiOS, Mac
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Questions about OneCalendar alternatives

What is the best alternative to OneCalendar?

Mozilla Thunderbird, number 1 in calendar apps with a score of 9.0 out of 10. The others here: Microsoft Outlook Calendar, Lark, EGroupware and 16 more.

What is the best free alternative to OneCalendar?

Mozilla Thunderbird is the best-ranked alternative with a free plan. 19 of the 20 alternatives here publish a free plan on their own pricing pages.

Is there an open-source alternative to OneCalendar?

Yes: Mozilla Thunderbird, EGroupware.

How are these alternatives ranked?

Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation.