DavMail - POP/IMAP/SMTP/Caldav to Exchange

•    Java

DavMail is a POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway allowing users to use any mail/calendar client (e.g. Thunderbird with Lightning or Apple iCal) with an Exchange server, even from the internet or behind a firewall through Outlook Web Access. DavMail now includes an LDAP gateway to Exchange global address book and user personal contacts to allow recipient address completion in mail compose window and full calendar support with attendees free/busy display.

Windows Live Calendar Gadget

Windows Live Calendar Gadget is a simple desktop calendar for Windows. It displays the events from internet calendars provided in iCalendar format.

SOGo - Fast and scalable modern collaboration suite (groupware)

•    Objective-C

SOGo is a very fast and scalable modern collaboration suite (groupware). It offers calendaring, address book management, and a full-featured Webmail client along with resource sharing and permission handling. It also makes use of documented standards (IMAP, CalDAV, CardDAV, etc.) and thereby provides native connectivity (without plugins) to many clients such as Microsoft Outlook, Apple iCal, the iPhone, Mozilla Lightning, and a plethora of mobile devices.

taskcal

•    Java

TaskCal Internet standards based human task management and process interaction. TaskCal is an iCalendar wrapper to the jBPM process manager, providing standards based calendar agent access to an actors tasks via email (iMIP), HTTP (.ics) and CalDav.

agendav - A CalDAV web client similar to Google Calendar

•    Javascript

AgenDAV is a CalDAV web client which features an AJAX interface to allow users to manage their own calendars and shared ones. It's released under the GPLv3 license.

Radicale - A simple CalDAV (calendar) and CardDAV (contact) server.

•    Python

A simple CalDAV (calendar) and CardDAV (contact) server.

agendav - A CalDAV web client similar to Google Calendar

•    PHP

A CalDAV web client similar to Google Calendar

Radicale - A simple CalDAV (calendar) and CardDAV (contact) server.

•    Python

Radicale is a free and open-source CalDAV and CardDAV server.

ICalendar

iCalendar is a standard (RFC 2445) for calendar data exchange. The standard is sometimes referred to as "iCal", which also is the name of the Apple, Inc. calendar program (see iCal) that provides one of the implementations of the standard. iCalendar allows users to send meeti...

Outlook to iCal Export Utility

•    VB

The outlook2ical utility is a VB macro that can be used to export a set of appointments from an Outlook Calendar to the iCal format for use with calendar clients such as PHP-iCalendar.

org-caldav - Caldav sync for Emacs orgmode

•    Emacs

Owncloud and Nextcloud: Regularly tested. Google Calendar: Should work, but you need to register an application with the Google Developer Console for OAuth2 authentication (see below).

ICS Deleter

•    Java

A small tool to delete old entries in a ICS-Calendar (*.ics) file. Simply choose a *.ics-file, choose a date until you want to delete the old entries and click on the delete button.

Delphi iCal non-visual component class.

•    Delphi

a non-visual delphi component to read/write iCal(ics) files.

palm2ical

•    Java

palm2ical is a Java program that converts Palm databases as stored on Windows into ical/ics files per RFC 2445, and specifically for the Apple iCal product. Note that this is a one-way conversion; there is no support for synchronizing Palm databases.

LotusNotes-Google Calendar Synchronizer

•    Java

This application synchronizes Lotus Notes Calendar entries with Google Calendar. GCal supports syncing with both iOS (iPhone/iPad/iPod) and Android devices, so you can now view your Lotus Notes calendar on your mobile device. GCal also allows you to view the calendar using any ical/rss/html compatible viewer. Currently the sync is only one direction: pushing Lotus Notes entries to GCal. All entries manually created in GCal will be ignored (and not copied down to Lotus Notes).

EventCalendar for Wordpress

•    PHP

Event Calendar plugin for Wordpress. Use Wordpress to manage future events as an online calendar. Display upcoming events in a dynamic calendar, on a listings page, or as a list in the sidebar. You can subscribe to the calendar from iCal or Sunbird.

wmCalendar

•    C

A calendar dockapp with monthly view and interface to iCal based calendars like Evolution or Mozilla calendar. Features: gregorian, persian and islamic calendar, moonphase, variable start of week, popup detail info about day events and app.launcher

iCalcreator

•    PHP

Open Source software (PHP) managing iCal (rfc2445) files, for non-calendar systems like CMS, project mgmt systems etc. able to manage calendar information like agendas, tasks, reports, totos, journaling data and communicate with calendar software.

GCALDaemon

•    Java

GCALDaemon is a Java program that offers two-way synchronization between Google Calendar and various iCalendar (RFC 2445) compatible calendar applications (Sunbird, Rainlendar, Apple iCal, Lightning, Evolution, KDE Kontact, Vista Calendar, etc).

Java iCal Group Scheduler

•    Java

Enables users to book meetings together automatically. Jical works with Evolution, Korganiser, Apple iCal, MS Outlook (for meetings). JiCal enhances your workgroup and personal calendar views. Shellscripts included for iCalendar to HTML/PDF/SVG/PNG/JPG.