Synchronize calendars and contacts Syncthing

Syncthing is an awesome tool.

In an attempt to use most open source software tools, I discovered that I like to have as much synchronization as possible in local storage (not on the internet).

Specifically have the laptop and the phone synchronized when they connect to the same network and regardless of the IP change.

One of the most difficult things is the contacts and calendars, for me between Linux and Android, which is only locally (not online) and that does not matter if the IP changes (sometimes I work at home, coffee, friends’ house, etc).

The only tool that works at the moment is DecSync CC that uses files that synchronize, for example using Syncthing.

Perhaps the negative is that it only works on Android and Evolution on Linux.

They can be used with other managers such as Thunderbird but adapting it with Radicale.

If someone has a better open source solution to synchronize contacts and calendars locally regardless of whether the IP changes please indicate it…

Radicale DecSync CC



If you have linux at hand you could use kopano (groupware) which is optimized to sync on Windows,Linux and phones via EAS protocol. I’m using it because Syncthing gets difficult if you sync databases as files between many devices. But: I’m not sure if an EAS server works well if you don’t have it as an always on device. This could lead to battery drain on phones is the server is unreachable.

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Thanks, kopano looks interesting, it’s similar to nextcloud.

But my interest is to have most things only local, not on the internet (even if I have my own server).

Basically, the phone is synchronized on the laptop, both are work tools.

Sometimes I work away from home and that is why I need the laptop and the phone to be synchronized even if the local IP changes (when I work in a cafe or at friends’ house, etc, both will be in the same “wifi”)

It’s just kind of like it. Kopano is a groupware with email, appointments, contacts, tasks, notes and complies with the Exchange standard and is therefore fully compatible with MS Outlook.

On Android systems I use the “Nine” app from 9Folders

the Exchange-compatible counterpart to Outlook and have everything in just 1 app and nothing else to synchronize.

And that is the main difference to ownCloud or nextCloud. Such software is firstly a data cloud software with APPs, with which something like Kopano could be mapped, but all APPs are extra, not integrated and not so easy to handle. It is the same on a smartphone. An app is required for everything, then you need add. a CalDAV app, etc., etc. All of this is complex.

I have been using the above solution with Kopano for years on Synology servers and on smartphones and tablets since Android v4 or v5, today I am with v10. I am very happy with it.


Thanks to this thread, I have finally managed to transfer calendars and contacts from Google to local files, so thank you very much @Usodiariom.

I did know about DecSync CC, but I was not aware of the possibility to use it together with Radicale. It does seem that the required plugin was released just a few weeks ago though. Also, to my surprise, setting Radicale up in Windows turned out to be extremely easy.

I would like to give a little warning in case you try to import an ICS file exported from Google Calendar. I had 7000+ events there, and importing them into Radicale with Thunderbird failed with a lot of errors in the Radicale console window. Because of that, I have eventually decided not to import them, but rather to use the ICS file directly for the past events, and use Radicale with DecSync for the new events. I will possibly transfer the old events manually later.

In addition, there is for read-only access to calendars in Android. It did crash too when processing my giant ICS calendar file, but will probably work fine for smaller ones.

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My problem is that my IP always changes, if you have a fixed local IP and you do not need to be in other places it will be very simple, the good thing about Radicale is that it does not need anything additional, nextcloud is very good but it needs PHP and MySQL and in android use DAVx5.

Thanks for the warning of large files.


What I have actually done is to install Radicale on each desktop PC separately, so as such it runs only on that specific PC locally. Then I sync the Radicale calendar and contact files themselves with Syncthing. This way the IP should not matter at all, should it?

In one word, there is no central server or anything like that, and the whole synchronisation process is being done by Syncthing.

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That means that you synchronize a folder with all the files, it seems interesting and you like the idea of how you have done it.

In my case I must use it with the android phone, so Radicale does not work for me unless I have a static IP, since Android will not take the .ics or .vcf file to synchronize, it only does it manually.

As I recall Radicale creates several .ics files

I was thinking of buying a raspberry pi zero w with just radical to do this function.

But with DecSync CC and syncthing I have the solution with the android phone

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No no, I probably did not express myself clearly. I thought that you meant that a static IP was needed for using Radicale with DecSync CC.

I only talked about Radicale on the desktop in the posting above. When it comes to Android, then following your explanation in this very thread, I have also installed DecSync CC on several Android devices and use Syncthing to transfer the DecSync folder, which itself is linked to Radicale on the desktops with the plugin.

All in all, my setup right now is probably very similar to yours.

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