HexGui
From HexWiki
HexGui is an application by Broderick Arneson to display a Hex game board, keep track of a game tree (a sequence of moves with variations), load and save games, attach a Hex strategy engine, and debug it. HexGui is written in Java and works on any operating system. HexGui can connect to any Hex strategy engine that supports the GTP protocol.
History
HexGui is a modified version of the open source application GoGui written in Java by Markus Enzenberger.
Availability
HexGui is no longer available from its original download site. A more recent version is available from GitHub.
Other software with the same name
There was also another program named HexGui and derived from GoGui, which used to be available from HexGui homepage. However, that link is now broken.