Editors and IDEs

An integrated development environment (IDE) is not implicitly required for programming in Fortran. In most cases, a free editor is sufficient, like:

The Fortran Wiki lists several more editors with syntax highlighting support for Fortran.

XWindow Programming Environment (xwpe)
Fig. 1: XWindow Programming Environment on FreeBSD

You may want to use one of the following free IDEs for your more sophisticated projects:

IntelliJ CLion with Fortran plug-in
Fig. 2: IntelliJ CLion with Fortran plug-in on FreeBSD

Some commercial IDEs feature Fortran support, like:

Vim

Please see :help fortran for information regarding syntax highlighting of Fortran source code in Vim. You can set some Fortran-specific variables in your .vimrc:

let fortran_free_source=1
let fortran_have_tabs=1
let fortran_more_precise=1
let fortran_do_enddo=1