You need Java to play the original java settlers of Catan online but it's obsolete so play the above one:
Click the green flag. Click custom game. Click create game then drag a human image to spot 2 and click the green check to start the game. Stamp cities and roads wherever you want. Press the arrow keys to change color/city. Click either die to roll; they don't do any thing, though. Once you roll the die, you can click next turn. Credit
Click "Practice" to play Settlers of Catan against Artifial Intelligent (AI) robots online on this server. Games expire after 90 minutes, use "*ADDTIME*" to extend a game. This online game is also known as jsettlers. Build settlements, roads, and cities by taking commodities such as wood, rocks, grain etc from the land around you.
Add this webgame to your Playzone!