Killendar Steve the Killer

Killendar keeps your appointments in a single file on your own machine, with optional SQLCipher AES-256 encryption at rest once you set a password. Month, week, day and agenda views, color categories, recurring appointments, and iCalendar import and export. Unlocked it is an ordinary SQLite database you can read, back up, or copy to another machine. Runs portable or installs for you or every user - no account, no sync, no telemetry. Open source under GPLv3.