This is the personal web page of Mats Sjöberg. I’m a computer science researcher (multimedia, machine learning). I care about digital rights and social justice issues. I like reading, walking and programming. I live in Espoo, Finland.

Contact details

E-mail (GPG: 8A9F94D8)
Social net. ( (GNU Social)
  @sazius (Twitter)
Chat (XMPP) (OTR: 98BC95FB 1E6CBC88 BA308EF7 DE14BFCD 28BEBE73)
IRC Sazius on freenode and IRCNet
Bitcoin 13e4fvsW3gu53pc7Ybqn7Vgwax7V7PaYLY (click to see QR code)
Photos (using MediaGoblin)
Personal web
Work web


This web page also hosts my blog. The most recent posts are:

Why I think should join the Federation
Posted 03 November 2014.

Handling mass subscriptions in GNU Social
Posted 17 August 2014.'s only-thread-originator-gets-notification problem and Pumpa's bad fix
Posted 31 July 2014.

Internal PuSH hub in Friendica to solve posting to StatusNet
Posted 20 November 2013.

Syncing MyKolab with Emacs org-mode
Posted 27 October 2013.


Here are links to some free software that I have created. If you find any bugs or have any questions about them, you can e-mail me at or use the bug trackers associated with each project.


Pumpa is a simple client written in C++ and Qt. Pumpa was mentioned on LWN: “Searching for a client”.

Pumpa’s documentation, source code and bug tracker are hosted on branchable.


A simple but addictive game in the Match-3 genre for the Nokia N9 (MeeGo Harmattan), newer Nokia Symbian phones (Anna and Belle operating systems). The game got over 100,000 downloads in the Nokia Ovi Store!

Kimmo Lindholm ported Heebo to the Jolla phone, and it has been highly popular also there.

Get Heebo from the Nokia Ovi Store for Nokia N9 or Nokia Symbian phones.

Heebo support page for N9 and Symbian.


A very simple client in Qt. It also includes a client for Nokia N9/N950, which is usable, but perhaps not quite ready for general adoption.

In November 2014 Stig Atle Steffensen took over as maintainer of the project.

Download for Nokia N9/N950: yaics_0.1.1_armel.deb (updated December 26, 2013).

Blog post about Harmattan Nokia N9/N950 client.


Very simple command line podcast client in Python, that I made for my personal use. I put it here in case someone else finds it useful.

The most recent code can be fetched from

JavaScript toys

ColourSOM is a simple HTML5 canvas + JavaScript application that demonstrates the Self-Organising Map algorithm by using random colours.

JSMandel just draws the Mandelbrot set, no zooming yet…

Miscellaneous links

Old fashioned list of links to stuff.

Web pages of friends and relatives

Niklas Gustafsson | Johan Paul | Anders Gustafsson
Åse och Micke | Kjell-Mikael Källman

Organisations I’m a member of

Amnesty | ATTAC | Skepsis ry
Electronic Frontier Finland ry | FSF | FSF Europe
ACM | IEEE | IEEE Finland Section | Pattern Recognition Society of Finland / IAPR