b>Summary: Cobweb is a Java applet for real-time network visualisation; its strength lies in enabling the interactive exploration of networks. Therefore, it allows new nodes to be interactively added to a network by querying a database on a server. The network constantly rearranges to provide the most meaningful topological view. Availability: Cobweb is available under the GPLv3 and may be freely downloaded at http://bioinformatics.charite.de/cobweb . Contact: joachim.eichborn@charite.de Supplementary Information: A tutorial, interactive examples, a downloadable example implementation of the applet and a video showing the applet are available at http://bioinformatics.charite.de/cobweb .