Doctran is a documentation generator for generating API documentation in HTML format from modern Fortran source code. It has full support for Fortran 95 standard and the object oriented parts of the Fortran 2003 standard.
The HTML format allows related documents to be conveniently hyper-linked together. Both breadcrumb and drop-down menu navigations are automatically generated to allow quick access to all parts of you source code.
More information is available here, and the user guide is available here.
Doctran depends on the following excellent libraries: