GLK is a portable API for programs with text user interfaces, especially interactive fiction interpreters. This allows programmers of an interpreter to write the interpreter in portable c code, link in the glk library, and compile the interpreter on several operating systems without much extra work.
The GLK library is currently available for the following operating systems and platforms:
Programs using GLK include Nitfol, Zeal, Floo, Tads, and hugo. The official GLK website is located at http://www.eblong.com/zarf/glk/