Compare software

Fastmail vs Proton Calendar: catalog facts
Fastmail	Proton Calendar
Paid Paid subscription with a 30-day free trial that needs no credit card.	Freemium Free account available, with paid Proton plans and a business version.
Android, iOS, Web	Android, iOS, Web
Email, calendar and contacts in one service Choice of EU or USA data residency	End-to-end encryption of event details Built-in scheduling for booking meetings
No free plan after the trial Hosted service, so your mail lives on Fastmail's servers	Requires a Proton account Works best within the Proton ecosystem
Downloadable app, Web application, Hosted service	Downloadable app, Web application, Hosted service
Closed source	Closed source
License not stated	License not stated
Account needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.