diff --git a/machines/deneb/configuration.nix b/machines/deneb/configuration.nix
index 9bf9ec2..5b3c951 100644
--- a/machines/deneb/configuration.nix
+++ b/machines/deneb/configuration.nix
@@ -25,6 +25,7 @@ in
     inputs.self.overlays.frappixLibsOverlay
     inputs.self.overlays.frappixPythonOverlay
     inputs.self.overlays.frappixToolsOverlay
+    inputs.self.overlays.frappixAppsOverlay
   ];
 
   fonts.packages = [ pkgs.tlwg ];
@@ -59,6 +60,7 @@ in
       pkgs.frappix.hrms
       pkgs.frappix.crm
       pkgs.frappix.posprinter
+      pkgs.frappix.default_thai_company
     ];
     sites = {
       "${sitename}" = {
@@ -69,6 +71,7 @@ in
           "hrms"
           "crm"
           "posprinter"
+          "default_thai_company"
         ];
       };
     };
diff --git a/overlays/default.nix b/overlays/default.nix
index 3a00279..62e5196 100644
--- a/overlays/default.nix
+++ b/overlays/default.nix
@@ -7,5 +7,6 @@
     frappixLibsOverlay = inputs.frappix.libsOverlay.x86_64-linux;
     frappixPythonOverlay = inputs.frappix.pythonOverlay.x86_64-linux;
     frappixToolsOverlay = inputs.frappix.toolsOverlay.x86_64-linux;
+    frappixAppsOverlay = import ../pkgs/frappix/overlay.nix;
   };
 }
diff --git a/pkgs/frappix/default-thai-company.nix b/pkgs/frappix/default-thai-company.nix
new file mode 100644
index 0000000..a8c3435
--- /dev/null
+++ b/pkgs/frappix/default-thai-company.nix
@@ -0,0 +1,35 @@
+{
+  buildPythonPackage,
+  pythonRelaxDepsHook,
+  flit-core,
+  mkAssets,
+  fetchFromGitea,
+}:
+let
+  version = "0.0.1";
+  src = fetchFromGitea {
+    domain = "git.b4l.co.th";
+    owner = "newedge";
+    repo = "default_thai_company";
+    rev = "caad6e77da35c9359b0dbd75ff0f39bb01891caf";
+    sha256 = "sha256-LH7E1EkecNPrhfQWSlWzPHHuJLM6SReCAifcFPDr61o=";
+  };
+in
+buildPythonPackage (finalAttrs: {
+  # pname doubles as the frappe app name (services.frappe reads app.pname)
+  pname = "default_thai_company";
+  inherit version;
+
+  pyproject = true;
+
+  src = mkAssets {
+    inherit (finalAttrs) pname version;
+    inherit src;
+    yarnHash = "sha256-oZgyP0hTU9bxszOVg3Bmiu6yos2d2Inc1Do8To4z8GQ=";
+  };
+
+  nativeBuildInputs = [
+    pythonRelaxDepsHook
+    flit-core
+  ];
+})
diff --git a/pkgs/frappix/overlay.nix b/pkgs/frappix/overlay.nix
new file mode 100644
index 0000000..0ade3c6
--- /dev/null
+++ b/pkgs/frappix/overlay.nix
@@ -0,0 +1,9 @@
+# Extends the frappix app scope with in-house frappe apps.
+# Must be applied after frappixFrappeOverlay (needs prev.frappix).
+final: prev: {
+  frappix = prev.frappix.overrideScope (
+    ffinal: _fprev: {
+      default_thai_company = ffinal.callPackage ./default-thai-company.nix { };
+    }
+  );
+}