• Latest version: qgraf-3.6.6 (May 2023).
  Please report any error you may happen to find.

• Programming language: Fortran 2008 for versions released since 2020 (qgraf-3.5+), and Fortran 77 for earlier versions.
  Executables/binaries are not distributed, the program has to be compiled and linked.
  Employing GNU Fortran for that task should be straightforward, eg there should be no need to specify a Fortran standard (see eg file qgraf-3.6.6.pdf). There are binary/executable versions of GFortran for several operating systems, as described in the GFortranBinaries webpage.

• The features added in the last two versions include (eg):
     inputing simple command-line arguments (3.5);
     generating multiple output-files in the same run (3.5);
     a more general loops statement (3.6);
     an extended language for describing input models (3.6);
     the partition statement (3.6).

• Current plans: qgraf-3.4 should be available and supported for some time yet (minimal fixes as need be), and qgraf-3.6 is now a stable version too; the Fortran and C interfaces should appear in the next version.

• Notice: for better future-proofing, packages that try to download this program should do so by using the URL that includes the "links" directory (as described in any recent manual, section ‘Automatic downloads’ or similar title) — or perhaps using it as an alternative URL.

Qgraf is based on the method described in the following paper:

• Automatic Feynman graph generation
  J. Comput. Phys. 105 (1993) 279–289
  https://doi.org/10.1006/jcph.1993.1074
  

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  This paper presents a concise description of an orderly algorithm for generating Feynman diagrams, on which Qgraf is based. In addition, it presents a diverse set of numbers — either the numbers of diagrams in certain sets or the sums of the respective symmetry factors — which may be employed to cross-check the correctness of Feynman diagram generators.

The next paper shows that the diagram generation with explicitly mixed propagators can be reduced to the usual one.

• Feynman graph generation and propagator mixing, I
  Comput. Phys. Commun. 269 (2021) 108103
  https://doi.org/10.1016/j.cpc.2021.108103
  

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  Given a QFT model A with explicitly mixed propagators, this paper shows how to construct a model A^⁎ without that kind of mixing, such that the Feynman diagrams in A can be easily derived from the diagrams in A^⁎ (by field re-naming, to be more precise). Moreover, it explains in detail why the method works; for example, it shows that if a diagram d^⁎ in A^⁎ gives rise to diagram d in A then d and d^⁎ have identical symmetry factors.