1. Find a package

You need a Fortran library that writes JSON. This chapter registers the index and finds one.

You need FoBiS.py 3.14.0 or newer (older versions cannot read this index):

pip install --upgrade FoBiS.py

Register the index

$ fobis index add szaghi https://github.com/szaghi/fortran-index
szaghi: 170 package(s), git index
Added index szaghi = https://github.com/szaghi/fortran-index to ~/.config/fobis/config.ini

szaghi is the name you give the index on your machine. It is cloned into ~/.fobis/indexes/szaghi and read from there, so searching is instant and works offline.

$ fobis index list
szaghi           git   user     2026-10-29T17:18:30+00:00  https://github.com/szaghi/fortran-index

Search

By words in the names, descriptions and keywords:

$ fobis search json
szaghi:json-fortran             https://github.com/jacobwilliams/json-fortran
    A Modern Fortran JSON API
szaghi:json-fortran-benchmarks  https://github.com/jacobwilliams/json-fortran-benchmarks
    Benchmarks for JSON Fortran parsers. Also comparison to Python.
szaghi:namelist2json            https://github.com/jacobwilliams/namelist2json
    Converting a Fortran namelist to JSON

Or by the Fortran module your code needs to use:

$ fobis search --module m_cli2
szaghi:general-purpose-fortran  https://github.com/urbanjost/general-purpose-fortran
    GPF (General Purpose Fortran)
szaghi:M_CLI2                   https://github.com/urbanjost/M_CLI2
    Unix-style commandline parsing using a prototype command

Look at one package

fobis info reads the package's source itself: its versions are the repository's tags, its modules those of the newest version.

$ fobis info json-fortran
json-fortran  (https://github.com/jacobwilliams/json-fortran)
  index     : szaghi
  summary   : A Modern Fortran JSON API
  license   : BSD
  build     : fpm
  versions  : 9.3.1, 9.3.0, 9.2.1, 9.2.0, 9.1.0, 9.0.5, 9.0.4, 9.0.3 (+45 older)
  modules   : json_file_module, json_kinds, json_module, json_parameters, json_string_utilities, json_value_module

json-fortran is an fpm package with 50-odd releases, and its library provides json_module. Next: use it in a project.