1.flectar / mailBuilt from the ground up for speed. Flectar Mail delivers native performance, instant startup, and about 20 MB of private memory at idle.androidcaldavcalendarcontactscross-platformdesktop-app+14 moreRustAGPL-3.01.8K total130 forks+93 starsfrom 1,673 · score 4.54
2.ridafkih / keeper.shCalendar sync tool & universal calendar MCP server. Aggregate, sync and control calendars on Google, Outlook, Office 365, iCloud, CalDAV or ICS.buncalendaricalnextjssynctypescript+10 moreTypeScriptAGPL-3.01.4K total74 forks+12 starsfrom 1,427 · score 2.56