Apollo is a user-friendly knowledge modelling application.
Modelling is based around the basic primitives, such as classes, instances, functions, relations etc. Internal model is build as a frame system according to the internal model of the OKBC protocol. Apollo does a full consistency check while editing.
Apollo is not bound to any knowledge representation language and can be adapted to support different storage formats via I/O plug-ins.
Apollo's user interface has an open architecture ( view based ) and allows for implementation of additional views of the knowledge base.
Apollo is written in the Java programming language and is available for a download.