khal
Calendar & ContactsCommand-line calendar built on CalDAV
Replaces Google Calendar
Best Lightweight Calendar & Contacts for self-hosting
The 12 best Lightweight calendar & contacts you can self-host, ranked by community traction.
vdirsyncer
Calendar & ContactsSynchronize calendars and contacts via CalDAV/CardDAV
Replaces iCloud sync
calcurse
Calendar & ContactsText-based calendar and scheduling application
Replaces Google Calendar
AgenDAV
Calendar & ContactsCalDAV web client with an Ajax interface
Replaces Google Calendar
Meeting scheduler nono Booked
Calendar & ContactsResource scheduling and reservation system
Replaces Skedda, Acuity Scheduling
Framadate
Calendar & ContactsOnline polling and meeting scheduling tool
Replaces Doodle
Xandikos
Calendar & ContactsGit-backed CalDAV and CardDAV server
Replaces Google Calendar, iCloud
Scheduling poll nono Nuages
Calendar & ContactsSelf-hosted meeting poll and availability finder
Replaces When2meet, Doodle
Tasks.org Server alt nono Calendarserver
Calendar & ContactsStandards-compliant calendar and scheduling server
Replaces Google Calendar, Exchange
EteSync DAV
Calendar & ContactsLocal CalDAV bridge for EteSync encrypted accounts
Replaces iCloud Calendar
InfCloud
Calendar & ContactsWeb client for CalDAV and CardDAV servers
Replaces Google Calendar web
Horde Kronolith
Calendar & ContactsCalendar application from the Horde groupware suite
Replaces Google Calendar, Exchange
No apps match these filters.
Every option here is open-source and self-hostable, tagged Lightweight within the calendar & contacts category. Compare them on the individual app pages for setup difficulty and resource requirements.