What is Proton Calendar?
| Category | Calendars |
|---|---|
| Company | Proton AG |
| Headquarters | Switzerland (EFTA) |
| Founded | 2014 |
| Ownership | Primary shareholder: Proton Foundation (non-profit) |
| Price | Free · Mail Plus $3.99 / month (yearly) · free plan: yes |
| Platforms | Web · iOS · Android · Windows · macOS · Linux |
| Open source | Yes |
| Data hosted in | Switzerland · own network |
| Alternative to | Google Calendar |
Who is behind Proton Calendar
Proton Calendar is an end-to-end encrypted calendar from Proton AG, based in Plan-les-Ouates near Geneva, Switzerland. Proton launched in the summer of 2014, founded by a team of scientists who met at CERN, after a crowdfunding campaign in which more than 10,000 people donated. Today Proton AG’s primary shareholder is the non-profit Proton Foundation, and Proton says it is funded by paying subscribers rather than advertising.
The calendar is part of the Proton account, alongside Proton Mail, Proton Drive, Proton VPN, Proton Pass and other apps. One login gives you all of them, and the calendar works together with your Proton Mail address for sending and receiving invitations.
Where Proton Calendar hosts your data
Proton says it is incorporated and headquartered in Switzerland and that all user data is protected by Swiss privacy law. Both the calendar web app (calendar.proton.me) and the main website run on Proton’s own network (Proton AG, AS62371), not on a US cloud.
| Domain | Used for | Hosting provider | ASN | Country |
|---|---|---|---|---|
| calendar.proton.me | calendar web app | Proton AG | AS62371 | Switzerland |
| proton.me | website | Proton AG | AS62371 | Switzerland |
Checked 25 Oct 2026. Hosting can change – report a change.
Proton Calendar pricing
Proton Calendar is included in every Proton plan. Proton Free gives you 3 personal calendars with end-to-end encryption and invitations. Mail Plus costs $3.99 a month billed yearly ($47.88 every 12 months), or $4.99 billed monthly, and raises the limit to 25 calendars, adds calendar sharing and one booking page for appointments, plus 15 GB of storage and a custom email domain. Proton Unlimited costs $9.99 a month billed yearly ($119.88) and adds 500 GB of storage, Proton VPN, Proton Pass and Proton Drive features on top. The pricing page I loaded showed US dollars; euro and Swiss franc prices are also offered.
Compared with Google Calendar, which is free with a Google account, Proton’s free plan covers the basics; you pay mainly for more calendars, sharing and booking pages.
Encryption and features
Proton encrypts all events end to end. The title, description, location and the people you invite are encrypted, so Proton cannot read them, and events you receive from people on other calendar services are stored with zero-access encryption. The apps for iPhone, Android, Windows, macOS, Linux and the web are open source, and Proton publishes an independent audit report for the calendar.
To move from Google, Proton’s Easy Switch tool imports your calendars, and events are encrypted as they arrive. Businesses get team calendars. Proton’s calendar page does not mention CalDAV, so you cannot plug Proton Calendar into Apple Calendar, Outlook or Thunderbird – you use Proton’s own apps.
What users say about Proton Calendar
Proton Calendar has no Trustpilot profile of its own. The Proton Mail profile, which also collects reviews about Proton accounts in general, has 2.1/5 from 1,802 reviews (checked 25 October 2026). Reviewers praise the privacy and the clean apps; the most common complaints are slow support and account lockouts.
Pros and cons
Pros of Proton Calendar
- Strong end-to-end encryption – titles, locations and guests included
- Easy Google import with Easy Switch
- Complete suite – mail, drive, VPN and passwords in one account
- Trustworthy open-source apps with a published audit
- Flexible apps for iPhone, Android, Windows, macOS, Linux and web
Cons of Proton Calendar
- Small free plan – 3 calendars, no sharing listed
- No CalDAV mentioned – no Apple Calendar or Outlook
- Weak support reputation on Trustpilot
- Restricted to a Proton account with a Proton Mail address
Verdict on Proton Calendar
Verdict: Proton Calendar is the most complete European calendar: Swiss, open source, end-to-end encrypted and as easy to use as Google’s. The trade-off is a closed system without CalDAV, and a free plan with only 3 calendars – most people who need sharing will end up on Mail Plus. Best for: anyone leaving Google Calendar who wants encrypted events and polished apps. Not for: people who want to keep Apple Calendar, Outlook or Thunderbird.
Proton Calendar is ranked #1 in Best European alternatives to Google Calendar and in Best European online calendars.
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Proton Calendar: FAQ
Is Proton Calendar free?
Yes. Proton Free includes Proton Calendar with 3 personal calendars and end-to-end encryption. Paid plans start with Mail Plus at $3.99 a month billed yearly and add up to 25 calendars, sharing and a booking page.
Is Proton Calendar a Swiss company?
Yes. Proton Calendar is made by Proton AG, headquartered near Geneva, Switzerland. Its primary shareholder is the non-profit Proton Foundation.
Can I import Google Calendar into Proton Calendar?
Yes. Proton’s Easy Switch tool imports your calendars from Google, and the events are encrypted once they arrive in Proton Calendar.
Is Proton Calendar better than Tuta Calendar?
Proton has a bigger free plan (3 calendars vs one), a direct Google import and a larger suite of apps. Tuta is cheaper with unlimited calendars from €3 a month, is based in the EU and uses quantum-safe encryption.
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Based on public pricing, documentation and user reviews · Changelog · Oct 2026: first version