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Proton Mail vs Fastmail: catalog facts
Proton Mail	Fastmail
Freemium Free accounts work in the mobile and web apps; the desktop apps are offered as a free…	Paid Paid subscription with a 30-day free trial that needs no credit card.
Windows, macOS, Linux, Android, iOS, Web	Android, iOS, Web
End-to-end encrypted email by default Apps for iOS, Android, macOS, Windows, Linux and the web	Email, calendar and contacts in one service Choice of EU or USA data residency
Only works with a Proton account Desktop apps need a paid plan after the trial	No free plan after the trial Hosted service, so your mail lives on Fastmail's servers
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.