Aso Brain Games
- Offer Xplorers Settlers, a java based version of Catan. Also offer Toulouse, Brainiac, and Roadblock. [Java]
- http://games.asobrain.com/

SourceForge.net: JSettlers
- Open source software for Java Settlers of Catan. Forum, bug tracking, screen shots, and downloads.
- http://sourceforge.net/projects/jsettlers/

jsettlers.com: Java Settlers of Catan
- Play ladder games, or random games versus humans and/or AI robots. Uses the JSettlers software, hosted on two servers at jsettlers.com.
- http://www.jsettlers.com/

Newman Server
- Java applet supporting real-time on-line play using the Columbus software. This is an alternate server intended to relieve crowding on the NWU server.
- http://settlers.servegame.com/

Yahoo Groups: Settlers of Catan
- Play by email for basic game and Cities and Knights expansion. Registration fee, requires download.
- http://groups.yahoo.com/group/settlers-of-catan/

NetSet: Network Settlers
- Play Settlers over the net. Program only runs on Windows systems.
- http://home.earthlink.net/~mgardner0/index.html

Settlers Project Website
- Play over the net. Requires Linux or Solaris.
- http://settlers.seul.org/