Open-source Google Calendar alternatives

Radicale is a lightweight CalDAV and CardDAV server for sharing calendars, to-do lists and contacts. It speaks CalDAV, CardDAV and HTTP, handles events, todos, journal entries and contact cards, and works with many calendar and contact clients.

It is meant to work out of the box without complicated setup. Access can be limited through authentication, connections can be secured with TLS, and all data is kept on the file system in a simple folder structure. Behavior can be extended with plugins, and the project provides documentation, a wiki and a discussion board.

Radicale is written in Python and distributed as free software under GPL-3.0. Because it needs only a file system for storage, it suits individuals, families and small teams who want to host their own calendar and address book instead of depending on a hosted provider.

DAVx5 is an open-source CalDAV and CardDAV synchronization app for Android. It keeps contacts, calendars and tasks on a phone in sync with a server that speaks those open standards, and it can also open online files over WebDAV through Android's Storage Access Framework. The project is focused on privacy and works with self-hosted servers as well as hosted ones.

Setup is designed to be easy, with automatic configuration for supported services. The project website lists the services DAVx5 has been tested with, along with a manual and an FAQ. Parts of the codebase have been split into reusable libraries: cert4android for custom certificate handling, dav4jvm as a WebDAV, CalDAV and CardDAV framework, and synctools for iCalendar and vCard processing.

The app is written in Kotlin and licensed under GPLv3. Support, contribution and security disclosure policies are documented, and news is posted on Mastodon. The README asks people who want to back development to donate or purchase the app, so the open-source edition coexists with a paid distribution.

Baikal is a calendar and contacts server that implements the CalDAV and CardDAV protocols. It lets you host your own calendars and address books and sync them with clients that speak those standards. It is written in PHP, based on the sabre project, and licensed under GPL-3.0. The latest release listed is 0.12.1.

Installation, upgrading and troubleshooting information is on the sabre.io project page. The README also links two detailed community tutorials written for people with little IT experience: a German guide that sets up Baikal on a Raspberry Pi and covers Thunderbird, Android with DAVx5, sharing calendars, database maintenance and security, and a French guide covering installation on Debian and iOS clients.

Baikal was created by Jérôme Schneider of Net Gusto together with fruux and is now developed by volunteers. It suits individuals, families and small groups who want to keep calendars and contacts on their own server rather than with a large provider. Upgrade instructions are provided for moving between versions.

Manage My Damn Life (MMDL) is a self-hosted front end for managing CalDAV tasks and calendars. It is a web app, built with Next.js, that talks to your existing CalDAV server, so your tasks and events stay on the server you already run. The project is in beta, so caution is advised with production data.

It supports subtasks and many task fields such as due date, status, description and recurrence, calendar event management, multiple CalDAV accounts and multiple user accounts. Tasks can be viewed as a list, in a Gantt view or on a calendar, and you can create task filters to see them as you prefer. It has OAuth support for CalDAV accounts, with Google Calendar supported, and a desktop-first, somewhat responsive layout. Planned features include full RFC 5545 field support, drag and drop, customizable views and plugins.

MMDL has been tested with Nextcloud, Radicale and Baikal and should work with servers supported by the tsdav library. It is licensed under GPL-3.0 and uses Weblate for translations.