f90doc

"f90doc is an easy-to-learn documentation tool for Fortran 90 written by Erik Demaine. Basically, it generates pages of HTML documentation from Fortran 90 source. The documentation is derived from comments prefixed with !! written (if desired) in a simple and intuitive documentation language whose source is easily readable in the code itself, while formatting nicely in HTML. f90doc is similar to javadoc, but does not require comments to be written in HTML.

The features:

• A useful (but simple) documentation language that is easily readable with a text editor and convertable into HTML, supporting lists, bold, italic, and verbatim text.
• module, subroutine, function, type, interface, and variable declarations, each of which can be commented.
• A table of contents for each top-level block (module, program, subroutine, or function), with links to the full description of each portion.
• use statements in modules, which generate links.
• call statements in programs, subroutines, and functions, which generate a list and optionally links.
• module procedure statements in interfaces, which generate links.
• Detection of public/privateness of module objects.

A couple of limitations: only free-form input files are supported, and only objects in modules are documented.

For more details on f90doc, including how to use it, see the documentation page.

For a quick start, you can look at the Fortran 90 code and resulting HTML documentation for a simple example."

http://erikdemaine.org/software/f90doc/

https://astro-informatics.github.io/s2/