A collection of Fortran interfaces to the most common Open Source GIS libraries, plus some more Fortran-specific tools. Please refer to the Github project page https://github.com/dcesari/fortrangis for more information.
In order to browse the API documentation, a good starting point is the Namespaces (i,e, MODULE in Fortran) menu. The documentation pages of the modules sometimes include the corresponding *_test.f90 source file which can be used as a commented example of use of the library.
Some additional information can be found in the howto pages How to build the library, How to import GLOBE DEM data with gdal/FortranGIS and How to retrieve metadata and RPC information with gdal/FortranGIS.