I've been using OwnCloud for a few months now, and I'm very happy with it. My own primary use for it has been to replace Google for syncing my contact lists and calendars, thanks to its CardDAV and CalDAV support, but I've also used it sparingly for file storage.

It certainly gives you a lot more flexibility than Dropbox: you can have access to your stored files via WebDAV, if you just want to directly access them on the network rather than sync. I haven't even installed the desktop sync client.

But at this stage, OwnCloud is definitely a solution for hackers and geeks rather than the general public. It's a self-hosted application, and doesn't always work well with shared hosting. I initially tried to get it running on my web hosting account, but eventually had to move it to my VPS due to OwnCloud not working well with the web host's Apache config. I also ran into a number of minor bugs that I had to correct in the source.

Overall, the release version seems more like a beta than a robust release at the moment, and even where it does work well, you certainly are exchanging "just works" for greater flexibility and configurability. Most of us may prefer to make that tradeoff in the direction that OwnCloud does, but I suspect that most Dropbox users wouldn't.

I tried latest version few days ago, but found relatively hard to configure, also I didn't find anything about encryption in the settings, and all files were stored on disk unencrypted, also the need to have a web UI looks to me like a security risk.

Does anyone can recommend service like that but without frontend? I'm really only interesed in syncying files between few of my computers and mobile devices.

You can probably just set up a web server with WebDAV support, mount that as a storage volume on your various devices, and use SSL to keep your transfers encrypted.

I used a 4.5.x version and at first it seemed like a good replacement for DropBox but the syncing doesn't seem up to par with Dropbox. Every now and then owncloud syncs hundreds of megabytes of data for unexplainable reasons, even worse it would create duplicates. Maybe because I jump around between many virtual machines, windows, mac and linux. The syncing gets confused. I never lost any data though.

If you used 4.5.x I encourage you to try the latest stable server (5.0.9) and client (1.3.0) again: http://owncloud.org/sync-clients/

Especially the duplicate issues are fixed with the 1.3.0 release.

I only looked quickly, but I didn't see anything about encryption on the site. Are you sure it's encrypted out of the box?

If you mean encrypted data storage on the server, you're better off just storing all its files in an encrypted volume using something tried and tested like dm-crypt rather than having to trust ownCloud to get it right.

I agree. I was just referring to the title of the link which mentions encryption, something I didn't find on the site linked.

I use the turnkey linux appliance and it has SSL enabled out of the box.

link:

http://www.turnkeylinux.org/owncloud

Out of the box, no. There are plugins, but they encrypt on the server side.

I tried ownCloud recently on a Raspberry Pi and found it dog slow. I'm not sure if I just found it at a bad time, or if it requires some more serious hardware, but it wasn't usable for me personally.

Make sure to install and activate php-apc (or some other accelerator).

While I don't have an RPi myself, a colleague of mine had his ownCloud instance go from dog slow to usable with that simple change.

The biggest factor I found was to turn off ajax-based workers and switch to cron. Also, disable any apps you aren't using.

Also, use MySQL instead of sqlite (This applies to ownCloud servers in general, too)