diff --git a/nixos/modules/services/web-apps/healthchecks.nix b/nixos/modules/services/web-apps/healthchecks.nix
index 1d439f162313..04b40e6eb8b0 100644
--- a/nixos/modules/services/web-apps/healthchecks.nix
+++ b/nixos/modules/services/web-apps/healthchecks.nix
@@ -213,8 +213,7 @@ in
           preStart = ''
             ${pkg}/opt/healthchecks/manage.py collectstatic --no-input
             ${pkg}/opt/healthchecks/manage.py remove_stale_contenttypes --no-input
-            ${pkg}/opt/healthchecks/manage.py compress
-          '';
+          '' + lib.optionalString (cfg.settings.DEBUG != "True") "${pkg}/opt/healthchecks/manage.py compress";
 
           serviceConfig = commonConfig // {
             Restart = "always";
diff --git a/pkgs/development/python-modules/oncalendar/default.nix b/pkgs/development/python-modules/oncalendar/default.nix
new file mode 100644
index 000000000000..5b4920a6cef7
--- /dev/null
+++ b/pkgs/development/python-modules/oncalendar/default.nix
@@ -0,0 +1,28 @@
+{ lib
+, buildPythonPackage
+, fetchFromGitHub
+, pytestCheckHook
+}:
+
+buildPythonPackage rec {
+  pname = "oncalendar";
+  version = "1.0";
+
+  src = fetchFromGitHub {
+    owner = "cuu508";
+    repo = "oncalendar";
+    rev = "refs/tags/v${version}";
+    hash = "sha256-eQYxOnL4/TJbY/nijcPl8TqK2MrwcdISKGfZQoI7828=";
+  };
+
+  nativeBuildInputs = [ pytestCheckHook ];
+
+  pythonImportsCheck = [ "oncalendar" ];
+
+  meta = with lib; {
+    description = "A systemd OnCalendar expression parser and evaluator";
+    homepage = "https://github.com/cuu508/oncalendar";
+    license = licenses.bsd3;
+    maintainers = with maintainers; [ phaer ];
+  };
+}
diff --git a/pkgs/servers/web-apps/healthchecks/default.nix b/pkgs/servers/web-apps/healthchecks/default.nix
index 193452c4354c..09f029930c3b 100644
--- a/pkgs/servers/web-apps/healthchecks/default.nix
+++ b/pkgs/servers/web-apps/healthchecks/default.nix
@@ -7,32 +7,35 @@
 let
   py = python3.override {
     packageOverrides = final: prev: {
-      django = prev.django_4;
+      django = prev.django_5;
     };
   };
 in
 py.pkgs.buildPythonApplication rec {
   pname = "healthchecks";
-  version = "2.10";
+  version = "3.3";
   format = "other";
 
   src = fetchFromGitHub {
     owner = "healthchecks";
     repo = pname;
     rev = "refs/tags/v${version}";
-    sha256 = "sha256-1x+pYMHaKgLFWcL1axOv/ok1ebs0I7Q+Q6htncmgJzU=";
+    sha256 = "sha256-XQ8nr9z9Yjwr1irExIgYiGX2knMXX701i6BwvXsVP+E=";
   };
 
   propagatedBuildInputs = with py.pkgs; [
+    aiosmtpd
     apprise
-    cron-descriptor
     cronsim
     django
     django-compressor
+    django-stubs-ext
     fido2
     minio
+    oncalendar
     psycopg2
     pycurl
+    pydantic
     pyotp
     segno
     statsd
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 1b75f9ac2059..b63de898f7c6 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -8965,6 +8965,8 @@ self: super: with self; {
 
   omrdatasettools = callPackage ../development/python-modules/omrdatasettools { };
 
+  oncalendar = callPackage ../development/python-modules/oncalendar { };
+
   ondilo = callPackage ../development/python-modules/ondilo { };
 
   onetimepass = callPackage ../development/python-modules/onetimepass { };