Valknut is a program that uses the Direct Connect protocol. It is compatible with other DC clients, such as the original DC from Neomodus, DC++ and derivatives. Valknut also interoperates with all common DC hub software. Valknut was originally written by Mathias Küster and is licensed under the terms of the GNU General Public License (GPL). It is written in C++ and uses the cross-platform Qt library for its GUI. Valknut compiles and runs on Linux, FreeBSD, Mac OS X, Microsoft Windows, and OS/2 - eComStation. During startup, the graphics of the splash screen show a Valknut.