Inferse
For vendors
AdvertiseTop spots, featured rows, home sponsor Get listedAdd a product we don't cover yet Claim a listingFree: verify the domain, then correct your page Vendor dashboardNumbers, orders and placements
List your platform
Vendor dashboard

Best Proton Calendar Alternatives in 2026

Updated

20 platforms from calendar apps ranked against Proton Calendar on the same published basis.

  1. 1
    Lark Free plan AndroidapiiOSLinuxMac 8.8
    Proton Calendar vs Lark
  2. 2
    Calendar.com Free plan AndroidapiextensioniOSWeb $20/mo8.8
    Proton Calendar vs Calendar.com
  3. 3
    Teamup Free plan AndroidapiiOSWeb $12/mo8.7
    Proton Calendar vs Teamup
  4. 4
    7shifts Free plan AndroidapiiOSWeb Free8.1
    Proton Calendar vs 7shifts
  5. 5
    Slotly Free plan AndroidapiWeb $0.83/mo7.9
    Proton Calendar vs Slotly
  6. 6
    Mozilla Thunderbird Free plan Open sourceAndroidLinuxMacWin Free7.6
    Proton Calendar vs Mozilla Thunderbird
  7. 7
    Microsoft Outlook Calendar Free plan AndroidiOSMacWeb $1.67/mo7.5
    Proton Calendar vs Microsoft Outlook Calendar
  8. 9
    Reclaim AI Free plan extensionWeb $10/mo7.4
    Proton Calendar vs Reclaim AI
  9. 10
    EGroupware Free trial Open sourceWebLinuxWinMac €21.90/mo7.4
    Proton Calendar vs EGroupware
  10. 11
    Notion Calendar Free plan AndroidiOS Free7.3
    Proton Calendar vs Notion Calendar
  11. 12
    Doodle Free plan Web $11/mo7.3
    Proton Calendar vs Doodle
  12. 13
    Cozi Free plan AndroidiOSWeb $3.25/mo7.3
    Proton Calendar vs Cozi
  13. 14
    Google Calendar AndroidiOS $7/mo7.2
    Proton Calendar vs Google Calendar
  14. 15
    Tuta Calendar Free plan AndroidiOS €3/mo7.2
    Proton Calendar vs Tuta Calendar
  15. 16
    Fantastical Free plan iOS Free7.2
    Proton Calendar vs Fantastical
  16. 17
    FlowSavvy Free plan AndroidiOSWeb 7.2
    Proton Calendar vs FlowSavvy
  17. 18
    Trevor AI Free plan Web $0.42/mo7.2
    Proton Calendar vs Trevor AI
  18. 19
    Samsung Calendar Free plan Android Free7.1
    Proton Calendar vs Samsung Calendar
  19. 20
    TimeTree Free plan AndroidiOSWeb $3.75/mo7.1
    Proton Calendar vs TimeTree
  20. 21
    DayFront apiself-hostedWeb 7.1
    Proton Calendar vs DayFront

Proton Calendar alternatives compared

#PlatformScoreFree planFromRuns on
1Lark8.8Free plan—Android, API, iOS, Linux, Mac, Web, Windows
2Calendar.com8.8Free plan$20/moAndroid, API, Browser, iOS, Web
3Teamup8.7Free plan$12/moAndroid, API, iOS, Web
47shifts8.1Free planFreeAndroid, API, iOS, Web
5Slotly7.9Free plan$0.83/moAndroid, API, Web
6Mozilla Thunderbird7.6Free planFreeAndroid, Linux, Mac, Windows
7Microsoft Outlook Calendar7.5Free plan$1.67/moAndroid, iOS, Mac, Web
9Reclaim AI7.4Free plan$10/moBrowser, Web
10EGroupware7.4No€21.90/moWeb, Linux, Windows, Mac
11Notion Calendar7.3Free planFreeAndroid, iOS
12Doodle7.3Free plan$11/moWeb
13Cozi7.3Free plan$3.25/moAndroid, iOS, Web
14Google Calendar7.2No$7/moAndroid, iOS
15Tuta Calendar7.2Free plan€3/moAndroid, iOS
16Fantastical7.2Free planFreeiOS
17FlowSavvy7.2Free plan—Android, iOS, Web
18Trevor AI7.2Free plan$0.42/moWeb
19Samsung Calendar7.1Free planFreeAndroid
20TimeTree7.1Free plan$3.75/moAndroid, iOS, Web
21DayFront7.1No—API, self-hosted, Web
Make your platform an alternative to Proton Calendar

The sponsored alternative slot on this page is labelled Sponsored.

See the price

Questions about Proton Calendar alternatives

What is the best alternative to Proton Calendar?

Lark, number 1 in calendar apps with a score of 8.8 out of 10. The others here: Calendar.com, Teamup, 7shifts and 16 more.

What is the best free alternative to Proton Calendar?

Lark is the best-ranked alternative with a free plan. 17 of the 20 alternatives here publish a free plan on their own pricing pages.

Is there an open-source alternative to Proton Calendar?

Yes: Mozilla Thunderbird, EGroupware.

How are these alternatives ranked?

Ranked on what each maker publishes, open and connectable first: a public API, open-source code, the depth of its documentation and a free tier to try it on. Model lists are sorted by the figure in their title, exactly as each provider publishes it.