Open-Source and Linux Calendars, Part 1

Fulfilling a New Year's promise to become more organized this year, I'm on the hunt for the best calendar program.

by Web Editor

While visiting my family in Pennsylvania this past holiday season, I had a realization: despite 31 years of thought to the contrary, in truth, I am not an organized person. This thought had been floating in my subconscious for a while, but this time I had misplaced the little stack of papers that contained my trip information, bills to pay, car rental confirmation number and tracking numbers for all the last-minute Christmas gifts I'd ordered on-line at 4 in the morning, 3 days before Christmas.

I had some free time that trip--there's not a whole lot going on in Dallas, PA, after 7pm--and I thought about all the occasions over the past year when I'd forgotten an acupuncture appointment, a Spanish class, a friend's birthday. I also thought about the late car insurance payments, the missed article deadlines (sorry again, Jill) and other details that I remembered after the fact.

I thought about all of these things and the toll they had taken on me in terms of stress, guilt and sleepless nights. I finally admitted that my almost-obsessive list-making tactic simply wasn't cutting it--I am disorganized. I'm not big on New Year's resolutions, so I made a new list titled "Things to Work on in 2006". It's less pressure that way in a make-or-break it kind of way. And at the top of that list is "Become More Organized".

So what does any of this have to do with you, Tux readers? I need a calendar application for my computer. I want it to be open-source and Linux because that's what my desktop runs. I want it to be easy to use, robust and flexible. I want to be able to make changes, add things and generally navigate through the calendar in an intuitive way.

Although I've worked with Linux for over six years now and probably could manage it, I don't want to download a ton of files, build everything and then spend many hours playing "hunt for the missing component". Like you, I don't want to spend most of my time with the application doing sysadmin; I want to use it and get on with things. Bottom line, I want a calendaring program that will improve my quality of life, not complicate it.

I'm not totally familiar with what's available in the realm of open-source calendaring applications. What I intend to do with this series of articles is make an informal investigation of what open-source calendar programs are available, what they offer and what their limitations are. I'll also let you know what the installation and set-up process is like for each.

In response, I'd like to hear from you about what you're looking for in a calendar program--do you want it offer many options or a few key ones? Do you want to be structured or more free-form? Also, if you have a calendar program to recommend--or suggestions about what to avoid--feel free to e-mail me or use the comments section below.

Currently, my list of calendar programs to test include Chandler, a still-in-development personal information management (PIM) application; the calendar portion of PHProjekt, an open-source group software suite; and Mozilla Calendar, an application extension that runs as part of another full Mozilla program installation (such as the Firefox Web browser). I'll also be testing Sunbird, which is the standalone version of Mozilla Calendar.

As you probably can tell, the programs I'm going to test drive are a mix of Web-based and standalone calendars. I'm not sure right now which is best for my needs, but I hope to figure that out as I go along. In turn, I hope you also will be able to gauge which method is better for your own calendaring needs.

I'll have the next installment of this experiment ready in a couple of weeks. In the meantime, let me know if you have any ideas and/or suggestions regarding my need to organize my life and my first step toward doing so.

Web Editor - Sun, 2021-01-15 21:27.

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VCalendar, an open source web calendar


I would like to recommend trying VCalendar. It is an open source Web calendar application with related tools, for posting and maintaining events and schedules online, in calendar format. Unlike any other online calendars, VCalendar comes with source code in PHP, ASP and ASP.NET (C# and VB.NET).


Alexey Petrov (not verified) - Wed, 2021-03-22 07:29.

For organizations purpose

Does anyone has experience with open exchange ?

al - (not verified) - M - , 2021-02-20 06:52.

Import Filters

I would hope a prominent feature included in your review is the inclusion, and effectiveness, of open source PIMs' import filters from other products such as Microsoft Outlook. In particular, I would be interested in the inclusion of import filters from WordPerfect Office's "Planner" PIM application.

JWilliamCupp (not verified) - Sun, 2021-02-19 15:54.

Sunbird/Mozcal wanting

I was using Mozilla Calendar add-on for Thunderbird for some time under 1.0x with decent success. It had some minor annoying bugs but seemed to usually work well (though it would sometimes keep popping up an alert for a long-past appointment that I repeatedly dismissed).

I then upgraded to FF and TB 1.5.x, and found to my dismay that, in the wonderfully disappointing world of Mozilla development backwards-compatibility, Mozilla Calendar did not work under 1.5.x and there is no new compatible version.

Installing standalone Sunbird was the only option. Unfortunately, it seems that the install of TB 1.5 blew away my old MozCal calendar data. In any case it's nowhere to be found. Plus, the recent build of Sunbird has more bugs than MozCal had. I've since downgraded to Sunbird 0.2, which seems more stable, though also with bugs. In any case, my old MozCal data is long gone.

You can't run a railroad with MozCal/Sunbird, that's for sure. Not past your next upgrade.

Keith T. (not verified) - Wed, 2021-02-01 12:57.

Organisation and calendars


1 Get a gmail account; email yourself everything of importance (travel info, ticket numbers, itinery etc.) This is searchable and available anywhere in the world.

2 Download and toast Puppy Linux live CD (60MB). This includes Ical and will save sessions back to the CD (or USB drive) if required. (I'm posting from Puppy now :~)

3 Don't forget to pack your CD - or better, attach your USB flash to your keyring. You wont need a computer - borrow anyone's, even a 486! If you lose it revert to 1 above.

General, and wish list:

The best e-calendar system I've had was the now (1999) defunct Sidekick for Windoze. Maybe not perfect, but I notice it still has a huge following on the web and is unfortunately a reason for my keeping that system available. I've got a massive database on mine and it does task lists, reminders, world time zones, mail-merge etc. If a gifted Linux developer is looking for a project, this could be a great model.

MikeF (not verified) - Wed, 2021-01-25 07:05.

Organization and calendars

I could not agree more: (1) emailing myself has saved my bacon many a time, and (2) Sidekick was and is a terrific little program that I still have, and I used it for keeping time for billing purposes in addition to the other many features it has.

Gary (not verified) - M - , 2021-01-30 10:29.


I don't need a very sophisticated calendar myself. I use them for the reminder features. A nice web base utility is Airset ( It would be everything I need if my cellular company would accept SRS messages.

Chuck (not verified) - Sat, 2021-01-21 04:22.

Calender features

The best ever (for me) PIM I ever used was Daytimer for Windows. Sadly that program is no longer supported and was never ported to XP so I have had to move on. I too have been searching for a replacement to that wonderful program in Linux, but also Windows ... hey, what ever gets the jobe done [g] I will be following this series with great interest. I am currently using Palm Desktop, but it has a few short comings, most notable is that it is a windows produce [wink]

Hope you can find something that works for you ... and hopefully me as well.


MikeD (not verified) - Fri, 2021-01-20 07:05.

calendar software reply

Have you tried evolution? Pretty close to that MS OL thing and getting better all the time. I am also watching with great interest. I am the IT Directotr at a public school in Indiana and am looking for a complete linux solution for collaboration. I believe that they might have gotten off to the right start. Beta 3 up now, and they seem to at least listen to users.

DaveG (not verified) - Wed, 2021-01-18 12:51.

OpenGroupware and Webcalendar

Calendaring is a timely topic for me. I have been looking for an
opensource (hack-able) calendaring package that allows personal as
well as community (one individual can schedule non-conflicting
meetings for several users) scheduling. Of course everyone wants
things like email notifications, meeting approvals, PDA transfers,
repeatable events with exceptions, etc.

From what I have found so far,
Opengroupware (ogo) and
WebCalendar(wc) seem to be the only ones that come close.

I'm a little concerned about the ability to scale to large numbers of
users. Ogo gives some performance statistics implying it may scale
better than wc.

We'll probably have to throw together some Perl programs to
automate account deletion/creation as people come and go.

It would also be cool to let students click a link to download
their class schedules from our college server directly into the
calendar (yes, we're a college).

So far, I did not see built-in secure LDAP support connections in
either, but it might be workable with something like stunnel or

The other thing I haven't seen in either is the ability to integrate
cleanly with web portal software.

Ogo appears to have the ability to assign individuals to groups
and manage access via group names. It also has built-in email,
project management, and a lot of other groupware and resource
management features that go beyond just calendaring.

Wc seems to work with a variety of database backends which
might make it more flexible in terms of data integrity, redundancy
and management.

In places, wc displays pop-ups listing what appears to be
every accessable user. This could become truly ugly in an
environment with a large number of users.

These things may turn out to be good opportunities to do some
hacking, and it looks to me like wc might be a lot easier to hack.

Hope this gives a few hints as to what I'd like to see in an
article discussing open source calendars.

Pete (not verified) - Wed, 2021-01-18 11:49.

Scaling WebCalendar

I have the same concern. WebCalendar's functionality is great, and it's
ability to work with a a large number of SQL database's adds considerable

The user pull down menus in WebCalendar are simply not practical
when the number of users is very large. Either, logic needs to be added to keep
the pull down list of users managable, or the pull down menu
needs to be replaced with the ability to just type in a user's name.

One way to keep the number of users small in a large installation would be
to expland the "Category" logic to allow a Category to be a group of users
sharing a common Calendar. User's would need the ability to either create a
new "Catagory", or to join an existing "Category". I am thinking a Category
then becomes a team, a group, a department, or just a group of people
with a common interest as a subset of a large number of users.

Probably, the more general approach would be to simply replace the
pull down user lists with the ability to type a user's name, and let WebCalendar
assist in completing a user's name to obtain the correct spelling and
to minimize typing.


Jim West (not verified) - Sun, 2021-01-28 16:23.


Ical is an X Window System based calendar program. Ical will easily
create/edit/delete entries, create repeating entries, remind you about
upcoming appointments, print and list item occurrences, and allow
shared calendars between different users. It has a to do list as well.
If you need portability between systems, this is possible as ical is
a Tcl/Tk application. It's also extensible and comes with some
contributed extensions. It comes with at least some distributions,
Mandriva being one of them.

Good luck...

Kevin the Drummer (not verified) - Wed, 2021-01-18 10:04.

Plans Calendar

I've always liked the looks of as it properly deals with multi-day events, much like Outlook does.

As for organization there's always the Getting Things Done and all of its variations ( and but I guess that's not really about calenders.

Kevin (not verified) - Wed, 2021-01-18 09:36.

You need the exact opposite of what you want

There are two aspects of "user friendliness" that are almost always mutually exclusive; easy to learn and easy to use.

I have found this rule to be true with most software. The easier it is to learn the more difficult it is to get it to do what I want. While a learning curve for an application will generally imply that it will be easier to get it to do what I want later on.

I have used evolution and sunbird. Both are excellent, but often fell short. I wanted to add a quick function or alter the display more than the config allowed. This meant I had to hack C, C++ or the confusing mess that is XUL. It was a hackers nightmare.

I stumbled onto planner, spent two days bashing my head against the wall (very hard and very frequently). However, now I have a PIM that does what I want when I want it. And if it doesn't its a couple quick hacks of elisp away.

Planner boils down to: what if you put calendaring functionality on top of a wiki and made it accessible anywhere and publishable to any format?

Planner hurts at first, but as with most things the pain is worth it.


Justin (not verified) - Wed, 2021-01-18 08:41.

Webcalendar and Openwebmail

We currently use a combination of webcalendar and openwebmail.
Webcalendar is easy for users to use and customize. Several offices use this to set up meetings and plan vacations and such. It can be imported directly into Evolution's calendar and several others.
I like the idea of having everything available and not having to deal with a thousand different clients. Webcalendar and OpenWebmail are the best solution I've been able to find so far. They are both easy to install and secure and when I get a tech support call I don't have to begin by asking what email client and version before debugging.
OpenWebmail has a calendar, but does not have calendar sharing (thus webmail). It is a useful personal calendar though. You can email notify and you can easily make the calendar notice a link to a an online conference.

Ashland (not verified) - Wed, 2021-01-18 05:14.


I am using KDE's KOrganizer under GNOME, and I am quite happy with it.

Another option can be GNOME's Evolution mail and calendar application.

An - ymous (not verified) - Wed, 2021-01-18 04:22.

It's all about the features

For me, the most important feature in a calendar is email reminders. Most calendars have pop-up reminders for appointments, but this is useless when you're not at your desk. I'm often somewhere else.

I have my StarOffice 5.2 calendar send a reminder to me as email to my pager, mobile phone, or email box. This way, no matter where I am, I get the reminder. This has been invaluable to avoid missing appointments.

Why StarOffice 5.2 (circa 1998) you may be asking? For some dumb reason, they took the calendar & email functionality out of the new versions. I keep an old Red Hat 7.2 box running so that I can continue to run this application. It's one of the best calendars I've used. (And now people are screaming that there's no good Outlook replacement - Waddup wit dat, Sun!?)

You can send multiple reminders to multiple people at multiple times. This is useful if you want to remind people 2 weeks in advance of a deadline, then 1 week in advance, then 1 day in advance. This may sound excessive, but this is how you really make use of a calender as a management tool. It's essential.

-2 weeks before project is due, send reminder email to various underlings
-1 week before project is due, email underlings to report progress
-2 days before project is due, email underlings to present run-through presentation
-1 hour before project is due, send message to underlings' pagers that presentation meeting is taking place.
-2 days _after_ project is due, underlings to present follow up to presentation responses

The last item illustrates an important feature missing from most calendars: reminders _after_ the event. Many times, a critical part of an action must take place after a meeting or event.

For each of the above reminders, StarOffice 5.2 allows you to send a customized message which is user-defined, including the ability to format the message w/ RTF or HTML. Each recipient can receive a different message. Very slick!

I checked Evolution, but it only allows sending email reminders if you have an Exchange-like backend. It doesn't work for stand-alone machines that don't have a backend email server - last time I checked, anyway.

On another machine, I use KOrganizer 3.4. It has nice To-Do List functionality. You create an item that needs to be done, and it stays persistent in your calendar until you mark it done. Again, this is essential. It needs to be *persistent* on the calendar until done - pop-ups are too easy to dismiss and forget. In other words, if you've entered a To-Do that states you need to backup the system on Wednesday, you will still see the item on Thurs, Fri, etc, until you've marked it Done.

KOrganizer is supposed to implement email reminders in v3.5, I believe, but that version isn't available yet for my Linux distro, so I haven't tested it.

Recurring To-Do's are required to avoid having to repeatedly enter information over and over.

E.g.: I own a Bar that has a perfomance space.

Every Wednesday, at 30 minutes prior to 8:00pm, send me a page to remind me to set up the stage for Open Mic. 2 hours later, send me a page to remind me to go reset the stage and lights for live music.

Every 1st & 2nd Monday of the month, 30 minutes prior to show time, send page to remind me to set up stage for comedy show.

Every 15th of month fax in performance schedule of events to local newspaper, etc...

I have an endess list of such things - recurring To-Do's are a can't-live-without.

Recurrence feature set is important. Some calendars won't let you set a recurrence to take place the third monday of the month. KOrganizer will let you set an event to take place the 3rd Thursday of September, every 3rd year. That's a little extreme, but I'm amazed at how many calendars won't do common types of recurrence.


Email reminders for both Appointments and To-Dos.
Reminders can be sent both before and after the incident.
Reminders can be sent to multiple parties w/ customizable messages.
Persistent To-Do's
Extensive Recurrence feature set

Cosmo Lee (not verified) - Tue, 2021-01-17 21:01.

another possibility

You might also consider JPilot. It is designed to sync with your PDA (Palm mostly, I think), but I use it as a stand alone program for keeping track of dates and appointments. There are also several plugins for things like syncing mail and tracking expenses. You can find out more at . Good luck with your search.

Walt H (not verified) - Tue, 2021-01-17 19:40.

Linux Calenders

Perhaps you're using the wrong version of Linux . (wink) I have simply Mepis and it has Kontact version 1.0.2 with a perfectly adequate calendar as much or little as I know about calendars. I'm presently using it as a worksite diary as well as for the occasional appointment. Seems quite intuitive to me.


Garry (not verified) - Tue, 2021-01-17 17:59.

Yes, kontact is definately

Yes, kontact is definately something to look at. It has all in one place, e-mail (if you like kmail, that is), address-list, calendar, task-list (including progress percentage and deadlines/reminders), notepad, birthday-dates, anniversaries, appointments and so forth. I think, kontact is quite well suited for everything short of full blown project management. I. e. quite sufficient for private use.

An - ymous (not verified) - Fri, 2021-02-17 05:26.


You might also have a look at webcalendar:

In addition to being a fairly powerful multi-user calendaring web application, the CVS version now supports both subscribing and publishing remotely. This means you can use your copy of mozilla calendar (or whathaveyou) to maintain your calendar when you are at your desk, and use the web interface when you are on the road.

There's also group-office to consider:

They have a GPL'ed branch of their commercial application. While I've found it to work extremely well in the past, their support is sorely lacking. Also, recent builts have caused errors in my older database.

dare2dreamer (not verified) - Tue, 2021-01-17 17:13.


This is an excellent calendar, following agreed standards and accessible on a wide range of platforms. It is well worth supporting such developments.

One thing, small but important to some people, is the ability to display an event over several days. Sunbird and some other calendars do this by repeating the same event on each day. Since there is very little space to describe an event in day view, it is considered valuable by some to be able to have the event linked across the consecutive days, allowing a longer description. This is done in one commercial calendar, and it would be good to see such features in some of the other calendars.


Ken Sarkies (not verified) - Tue, 2021-01-17 17:03.


Try Webcalendar, It's a php based web based open source back end calendar. It should work with Sunbird, or any other webcal enabled calendar.

Larry Wade (not verified) - Tue, 2021-01-17 16:20.

Calendar programs

I recommend using a calendar that can be sync'd with a Palm. That way you always have it with you.

celem (not verified) - Tue, 2021-01-17 14:12.

PIM compatibility

Is there any glimmer of a possibility that an existing or coming calendaring application will take uploads from (and download to) a Palm Pilot or such like?

An - ymous (not verified) - Wed, 2020-06-28 12:42.

OSS Calendar Programs

I have been so well-pleased with Sunbird that I just can't say enough about it. It's user-friendly, a cinch to install (at least for Mandriva 2006 and MS-Windows), and it has made my son and daughter's hectic college and high school schedules managable.

Now if it could just remind the wife to pay bills on time, it would be perfect.

Terry (not verified) - Tue, 2021-01-17 13:49.

Yahoo! Calendar Rocks

I have been a die hard Yahoo! fan since 1998. They have everything I need to stay organized. It's free, although a pay service is available for a nominal fee, and is always available. I'm a Windows Administrator who loves to run Linux (FC4) at home. I love that I can access my email, Calendar, Notes, Address Book, etc. from anywhere on any OS with any web browser. I've used Firefox for the past 2 years and have never had any issues accessing any of Yahoo!'s content with the exception of some of their games.

Yahoo! Calendar is my recommendatoion.


Steve Correia (not verified) - M - , 2021-01-16 08:40.


I don't need a very sophisticated calendar myself. I use them for the reminder features. A nice web base utility is Airset ( It would be everything I need if my cellular company would accept SRS messages.

טיסות (not verified) - M - , 2020-08-21 07:30.


Start with Sunbird.
End with Sunbird.

It's a great program.
Has worked flawlessly for me for the last 7 months.
Get plugins for Firefox and Thunderbird and you can access your calendar right from within both of them. In fact, I've made my Home page this month's calendar and have Firefox display that when it opens up --- great way to be reminded to check your calendar.

My data is also saved on vfat drive and is shared so that the exact same data can be opened up in Sunbird for Windows. That assures me that the data can always be accessed !

If you [i]must[/i] try other things, I hear that Mozilla suite is about to be discontinued in favor of a new suite ... SEAMONKEY ...

Good luck.

-- Brent

Brent (not verified) - M - , 2021-01-16 04:47.


WebCalendar ended up being a disappointment. It is not intuitive and the appearance isn't acceptable. I can see it becoming useable if we get in and modify all of the CSS, colors, and graphics.

I tried Sunbird out but that it was buggy and prone to crashing on OSX. This is to be expected, considering that it is pre-release software. I am downloading a newer release as I type this in the hope that various problems are corrected (continually bouncing in the dock and never launching is one problem I can think of).

An - ymous (not verified) - Tue, 2021-01-17 16:38.