Tan Go

TanGo is an old client for playing on IGS and NNGS, and also an interface for playing against GnuGo (included).

The old URL was http://www.amourtan.com/ . The software still appears to be available from https://tangoclient.sourceforge.net/ (as of early 2024). But nowadays most people will prefer to use a more modern client such as GoPanda.