Qgraf is a computer program that generates Feynman diagrams for various types of QFT models — it is a research tool created with the obvious aim of contributing to extend the range of feasible, perturbative QFT calculations. Diagrams are represented by symbolic expressions only (nevertheless, if some kind of graphical representation is required, have a look at the external links).

• Latest version: qgraf–3.4.2 (2019).
  Please report any error you may happen to find.

• Programming language: Fortran (mostly fortran 77; valid Fortran 95 syntax, though).
  Binaries/executables are not distributed, the program has to be compiled and linked;
  employing GNU's GFortran for that task should be straightforward, eg there should be
  no need to specify a Fortran standard.

• The features added since the release of qgraf–3.1.5 include:
  option “onshellx”, an extended form of “onshell” (3.2);
  improved treatment of duplicate vertices (3.3);
  a way of restricting the configuration of external lines (3.3);
  the ability to require/disallow bridge-type propagators with certain momenta (3.3);
  an option to select diagrams with non-factorizable cycle spaces (3.4);
  an option to select 1–vertex irreducible diagrams (3.4).

• Current plans: qgraf–3.4 should be the next ‘stable’ version (ie available for a long
  period, minimal fixes as need be), hopefully replacing qgraf–3.1 in that regard.

  The next release, likely to be available in the first half of 2021, should bring mostly
  ‘technical’ (ie diagram unrelated) improvements. Other planned features will be
  delayed until the subsequent release.

The diagram generation is based on the method described in the following article:

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