Cooperative calendars you can self-host. A public shelf over the FOSS calendars catalog — 15 self-hostable open-source calendars across mobile, desktop, server and sync, plus 3 Infinity-Labs own tools. Not products to buy, but software to run, own and adapt.
catalog.foss.systems — INgest, don't duplicate: it points, the upstreams own the code.
Every card is a self-hostable FOSS calendar from
catalog.foss.systems/calendars — grouped by where it runs. Cards point
out at each project's own homepage or repository; nothing here is
embedded or owned. Pick one, run it yourself.
Android and mobile calendar apps and widgets
Material-design open source Android calendar with monthly/weekly/daily/agenda views and CalDAV, Google and Exchange sync.
Fork of Simple Calendar maintained by the Fossify organization with continued FOSS development; CalDAV, widgets and recurring events.
Simple Android calendar with events, customizable widget and optional CalDAV synchronization, recurring events and reminders.
Android home-screen widgets that display configured lists of calendar events and tasks with customizable settings.
Desktop calendar clients and PIM suites
Built-in calendar in the Mozilla Thunderbird mail client with CalDAV/CardDAV, tasks, recurring events and offline support across platforms.
Calendar and scheduling program from the KDE Kontact suite; CalDAV, multiple calendars and Akonadi backend.
Simple, modern calendar for GNOME with Evolution Data Server integration and online-account support.
GNOME personal-information manager providing email, calendar, address book and tasks with CalDAV/CardDAV and Exchange support.
Self-hosted CalDAV/CardDAV calendar servers
Full-featured calendar app for Nextcloud with CalDAV, sharing, public calendars and contacts/tasks integration.
Small but powerful CalDAV and CardDAV server in Python; simple to install, file-based storage, rights management.
Lightweight CalDAV and CardDAV server based on SabreDAV with web-based administration and MySQL/SQLite backends.
Web groupware and embeddable web calendars
Comprehensive PHP groupware suite with webmail, address book and calendar, CalDAV/CardDAV and mobile sync.
Embeddable web calendar you can add to your own website; customizable and responsive.
Simple group calendar application packaged for easy self-hosted deployment.
Calendar/contact sync bridges
Infinity Labs sovereign calendar tools
Sovereign iCalendar edge — publish and subscribe to plain .ics feeds. Self-hostable.
Booking and scheduling front — a MIT-licensed Cal.com fork. Self-hostable.
Django discovery front that helps you find and compare FOSS calendar applications.
This page is thin by construction. A portal is render(iCatalog, lens=<category>) — one shared catalog, filtered to a single category and drawn as a shelf. Point the cal lens at the catalog and you get this. Point a different lens and you get agents, chat, task or maps. Same move, different filter.
One catalog, many category renderings — the shelf is data, not a bespoke app.
A portal = render(iCatalog, lens). The calendar shelf is not an exception to that rule — it is the rule, filtered to lens=cal.