diff --git a/pkgs/development/python-modules/gaphas/default.nix b/pkgs/development/python-modules/gaphas/default.nix
new file mode 100644
index 000000000000..a6351aeeadd7
--- /dev/null
+++ b/pkgs/development/python-modules/gaphas/default.nix
@@ -0,0 +1,45 @@
+{ lib
+, buildPythonPackage
+, pythonOlder
+, fetchPypi
+, poetry-core
+, gobject-introspection
+, gtk3
+, pycairo
+, pygobject3
+, typing-extensions
+}:
+
+buildPythonPackage rec {
+  pname = "gaphas";
+  version = "3.1.9";
+  disabled = pythonOlder "3.7";
+
+  format = "pyproject";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "sha256-S6cRsfqXYM4mSVSs2M8fET5ShFClKkGkod2w2y6F2gc=";
+  };
+
+  nativeBuildInputs = [
+    poetry-core
+  ];
+
+  buildInputs = [ gobject-introspection gtk3 ];
+
+  propagatedBuildInputs = [
+    pycairo
+    pygobject3
+    typing-extensions
+  ];
+
+  pythonImportsCheck = [ "gaphas" ];
+
+  meta = with lib; {
+    description = "GTK+ based diagramming widget";
+    maintainers = with maintainers; [ wolfangaukang ];
+    homepage = "https://github.com/gaphor/gaphas";
+    license = licenses.asl20;
+  };
+}
diff --git a/pkgs/development/python-modules/generic/default.nix b/pkgs/development/python-modules/generic/default.nix
new file mode 100644
index 000000000000..87dca630a1b8
--- /dev/null
+++ b/pkgs/development/python-modules/generic/default.nix
@@ -0,0 +1,32 @@
+{ lib
+, buildPythonPackage
+, pythonOlder
+, fetchPypi
+, poetry-core
+}:
+
+buildPythonPackage rec {
+  pname = "generic";
+  version = "1.0.1";
+  disabled = pythonOlder "3.7";
+
+  format = "pyproject";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "sha256-ex93I+ofo5lP6qoolZwzjxSspeqJimY3vpB32RLJ00k=";
+  };
+
+  nativeBuildInputs = [
+    poetry-core
+  ];
+
+  pythonImportsCheck = [ "generic" ];
+
+  meta = with lib; {
+    description = "Generic programming (Multiple dispatch) library for Python";
+    maintainers = with maintainers; [ wolfangaukang ];
+    homepage = "https://github.com/gaphor/generic";
+    license = licenses.bsdOriginal;
+  };
+}
diff --git a/pkgs/tools/misc/gaphor/default.nix b/pkgs/tools/misc/gaphor/default.nix
new file mode 100644
index 000000000000..6105b07c3450
--- /dev/null
+++ b/pkgs/tools/misc/gaphor/default.nix
@@ -0,0 +1,66 @@
+{ lib
+, buildPythonApplication
+, fetchPypi
+, poetry-core
+, gobject-introspection
+, pango
+, gtksourceview4
+, wrapGAppsHook
+, makeDesktopItem
+, copyDesktopItems
+, gaphas
+, generic
+, pycairo
+, pygobject3
+, python
+, tinycss2
+}:
+
+buildPythonApplication rec {
+  pname = "gaphor";
+  version = "2.6.5";
+
+  format = "pyproject";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "sha256-IFsbWx5lblKsnEibVihM6ZPRoydXC+JM1gdZEUUTKxw=";
+  };
+
+  nativeBuildInputs = [
+    poetry-core copyDesktopItems gobject-introspection wrapGAppsHook
+  ];
+
+  # Setting gobject-introspection on booth nativeBuildInputs and
+  # buildInputs because of #56943. This recognizes pango, avoiding
+  # a "ValueError: Namespace PangoCairo not available".
+  buildInputs = [ gobject-introspection gtksourceview4 pango ];
+
+  propagatedBuildInputs = [
+    gaphas
+    generic
+    pycairo
+    pygobject3
+    tinycss2
+  ];
+
+  desktopItems = makeDesktopItem {
+    name = pname;
+    exec = "gaphor";
+    icon = "gaphor";
+    comment = meta.description;
+    desktopName = "Gaphor";
+  };
+
+  postInstall = ''
+    install -Dm644 $out/${python.sitePackages}/gaphor/ui/icons/hicolor/scalable/apps/org.gaphor.Gaphor.svg $out/share/pixmaps/gaphor.svg
+  '';
+
+  meta = with lib; {
+    description = "Simple modeling tool written in Python";
+    maintainers = with maintainers; [ wolfangaukang ];
+    homepage = "https://github.com/gaphor/gaphor";
+    license = licenses.asl20;
+    platforms = [ "x86_64-linux" ];
+  };
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index d47c983727d7..c443843f4bdc 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5392,6 +5392,8 @@ with pkgs;
 
   gandom-fonts = callPackage ../data/fonts/gandom-fonts { };
 
+  gaphor = python3Packages.callPackage ../tools/misc/gaphor { };
+
   garmin-plugin = callPackage ../applications/misc/garmin-plugin {};
 
   garmintools = callPackage ../development/libraries/garmintools {};
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index ee1258aa64a1..0778987c85d0 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -2968,6 +2968,8 @@ in {
     pythonPackages = self;
   });
 
+  gaphas = callPackage ../development/python-modules/gaphas { };
+
   garminconnect-aio = callPackage ../development/python-modules/garminconnect-aio { };
 
   garminconnect-ha = callPackage ../development/python-modules/garminconnect-ha { };
@@ -3006,6 +3008,8 @@ in {
 
   genanki = callPackage ../development/python-modules/genanki { };
 
+  generic = callPackage ../development/python-modules/generic { };
+
   genome-collector = callPackage ../development/python-modules/genome-collector { };
 
   genpy = callPackage ../development/python-modules/genpy { };