diff --git a/nixos/modules/module-list.nix b/nixos/modules/module-list.nix
index a014c93afedec..bc5f872dd3b6e 100644
--- a/nixos/modules/module-list.nix
+++ b/nixos/modules/module-list.nix
@@ -1482,6 +1482,7 @@
   ./services/web-apps/ocis.nix
   ./services/web-apps/onlyoffice.nix
   ./services/web-apps/openvscode-server.nix
+  ./services/web-apps/open-web-calendar.nix
   ./services/web-apps/mobilizon.nix
   ./services/web-apps/openwebrx.nix
   ./services/web-apps/outline.nix
diff --git a/nixos/modules/services/web-apps/open-web-calendar.nix b/nixos/modules/services/web-apps/open-web-calendar.nix
new file mode 100644
index 0000000000000..525c9eb8c28cd
--- /dev/null
+++ b/nixos/modules/services/web-apps/open-web-calendar.nix
@@ -0,0 +1,162 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  inherit (lib)
+    mkIf
+    mkOption
+    mkEnableOption
+    mkPackageOption
+    mkDefault
+    types
+    concatMapStringsSep
+    generators
+    ;
+  cfg = config.services.open-web-calendar;
+
+  nixosSpec = calendarSettingsFormat.generate "nixos_specification.json" cfg.calendarSettings;
+  finalPackage = cfg.package.override {
+    # The calendarSettings need to be merged with the default_specification.yml
+    # in the source. This way we use upstreams default values but keep everything overridable.
+    defaultSpecificationFile = pkgs.runCommand "custom-default_specification.yml" { } ''
+      ${pkgs.yq}/bin/yq -s '.[0] * .[1]' ${cfg.package}/${cfg.package.defaultSpecificationPath} ${nixosSpec} > $out
+    '';
+  };
+
+  inherit (finalPackage) python;
+  pythonEnv = python.buildEnv.override {
+    extraLibs = [
+      (python.pkgs.toPythonModule finalPackage)
+      # Allows Gunicorn to set a meaningful process name
+      python.pkgs.gunicorn.optional-dependencies.setproctitle
+    ];
+  };
+
+  settingsFormat = pkgs.formats.keyValue { };
+  calendarSettingsFormat = pkgs.formats.json { };
+in
+{
+  options.services.open-web-calendar = {
+
+    enable = mkEnableOption "OpenWebCalendar service";
+
+    package = mkPackageOption pkgs "open-web-calendar" { };
+
+    domain = mkOption {
+      type = types.str;
+      description = "The domain under which open-web-calendar is made available";
+      example = "open-web-calendar.example.org";
+    };
+
+    settings = mkOption {
+      type = types.submodule {
+        freeformType = settingsFormat.type;
+        options = {
+          ALLOWED_HOSTS = mkOption {
+            type = types.str;
+            readOnly = true;
+            description = ''
+              The hosts that the Open Web Calendar permits. This is required to
+              mitigate the Host Header Injection vulnerability.
+
+              We always set this to the empty list, as Nginx already checks the Host header.
+            '';
+            default = "";
+          };
+        };
+      };
+      default = { };
+      description = ''
+        Configuration for the server. These are set as environment variables to the gunicorn/flask service.
+
+        See the documentation options in <https://open-web-calendar.quelltext.eu/host/configure/#configuring-the-server>.
+      '';
+    };
+
+    calendarSettings = mkOption {
+      type = types.submodule {
+        freeformType = calendarSettingsFormat.type;
+        options = { };
+      };
+      default = { };
+      description = ''
+        Configure the default calendar.
+
+        See the documentation options in <https://open-web-calendar.quelltext.eu/host/configure/#configuring-the-default-calendar> and <https://github.com/niccokunzmann/open-web-calendar/blob/master/open_web_calendar/default_specification.yml>.
+
+        Individual calendar instances can be further configured outside this module, by specifying the `specification_url` parameter.
+      '';
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+
+    assertions = [
+      {
+        assertion = !cfg.settings ? "PORT";
+        message = ''
+          services.open-web-calendar.settings.PORT can't be set, as the service uses a unix socket.
+        '';
+      }
+    ];
+
+    systemd.sockets.open-web-calendar = {
+      before = [ "nginx.service" ];
+      wantedBy = [ "sockets.target" ];
+      socketConfig = {
+        ListenStream = "/run/open-web-calendar/socket";
+        SocketUser = "open-web-calendar";
+        SocketGroup = "open-web-calendar";
+        SocketMode = "770";
+      };
+    };
+
+    systemd.services.open-web-calendar = {
+      description = "Open Web Calendar";
+      after = [ "network.target" ];
+      environment.PYTHONPATH = "${pythonEnv}/${python.sitePackages}/";
+      serviceConfig = {
+        Type = "notify";
+        NotifyAccess = "all";
+        ExecStart = ''
+          ${pythonEnv.pkgs.gunicorn}/bin/gunicorn \
+            --name=open-web-calendar \
+            --bind='unix:///run/open-web-calendar/socket' \
+            open_web_calendar.app:app
+        '';
+        EnvironmentFile = settingsFormat.generate "open-web-calendar.env" cfg.settings;
+        ExecReload = "kill -s HUP $MAINPID";
+        KillMode = "mixed";
+        PrivateTmp = true;
+        RuntimeDirectory = "open-web-calendar";
+        User = "open-web-calendar";
+        Group = "open-web-calendar";
+      };
+    };
+
+    users.users.open-web-calendar = {
+      isSystemUser = true;
+      group = "open-web-calendar";
+    };
+
+    services.nginx = {
+      enable = true;
+      virtualHosts."${cfg.domain}" = {
+        forceSSL = mkDefault true;
+        enableACME = mkDefault true;
+        locations."/".proxyPass = "http://unix:///run/open-web-calendar/socket";
+      };
+    };
+
+    users.groups.open-web-calendar.members = [ config.services.nginx.user ];
+
+  };
+
+  meta.maintainers = with lib.maintainers; [ erictapen ];
+
+}
diff --git a/nixos/tests/all-tests.nix b/nixos/tests/all-tests.nix
index 3fcc429f3478f..f5a5fa37772f7 100644
--- a/nixos/tests/all-tests.nix
+++ b/nixos/tests/all-tests.nix
@@ -745,6 +745,7 @@ in {
   openstack-image-userdata = (handleTestOn ["x86_64-linux"] ./openstack-image.nix {}).userdata or {};
   opentabletdriver = handleTest ./opentabletdriver.nix {};
   opentelemetry-collector = handleTest ./opentelemetry-collector.nix {};
+  open-web-calendar = handleTest ./web-apps/open-web-calendar.nix {};
   ocsinventory-agent = handleTestOn [ "x86_64-linux" "aarch64-linux" ] ./ocsinventory-agent.nix {};
   owncast = handleTest ./owncast.nix {};
   outline = handleTest ./outline.nix {};
diff --git a/nixos/tests/web-apps/open-web-calendar.nix b/nixos/tests/web-apps/open-web-calendar.nix
new file mode 100644
index 0000000000000..b5cd59c56abdf
--- /dev/null
+++ b/nixos/tests/web-apps/open-web-calendar.nix
@@ -0,0 +1,51 @@
+import ../make-test-python.nix (
+  { pkgs, ... }:
+
+  let
+    certs = import ../common/acme/server/snakeoil-certs.nix;
+
+    serverDomain = certs.domain;
+  in
+  {
+    name = "open-web-calendar";
+    meta.maintainers = with pkgs.lib.maintainers; [ erictapen ];
+
+    nodes.server =
+      { pkgs, lib, ... }:
+      {
+        services.open-web-calendar = {
+          enable = true;
+          domain = serverDomain;
+          calendarSettings.title = "My custom title";
+        };
+
+        services.nginx.virtualHosts."${serverDomain}" = {
+          enableACME = lib.mkForce false;
+          sslCertificate = certs."${serverDomain}".cert;
+          sslCertificateKey = certs."${serverDomain}".key;
+        };
+
+        security.pki.certificateFiles = [ certs.ca.cert ];
+
+        networking.hosts."::1" = [ "${serverDomain}" ];
+        networking.firewall.allowedTCPPorts = [
+          80
+          443
+        ];
+      };
+
+    nodes.client =
+      { pkgs, nodes, ... }:
+      {
+        networking.hosts."${nodes.server.networking.primaryIPAddress}" = [ "${serverDomain}" ];
+
+        security.pki.certificateFiles = [ certs.ca.cert ];
+      };
+
+    testScript = ''
+      start_all()
+      server.wait_for_unit("open-web-calendar.socket")
+      server.wait_until_succeeds("curl -f https://${serverDomain}/ | grep 'My custom title'")
+    '';
+  }
+)