diff --git a/nixarr/audiobookshelf/default.nix b/nixarr/audiobookshelf/default.nix
new file mode 100644
index 0000000..f7b00ed
--- /dev/null
+++ b/nixarr/audiobookshelf/default.nix
@@ -0,0 +1,241 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+with lib; let
+  cfg = config.nixarr.audiobookshelf;
+  nixarr = config.nixarr;
+in {
+  options.nixarr.audiobookshelf = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      example = true;
+      description = ''
+        Whether or not to enable the Audiobookshelf service.
+
+        **Conflicting options:** [`nixarr.plex.enable`](#nixarr.plex.enable)
+      '';
+    };
+
+    package = mkPackageOption pkgs "audiobookshelf" {};
+
+    stateDir = mkOption {
+      type = types.path;
+      default = "${nixarr.stateDir}/audiobookshelf";
+      defaultText = literalExpression ''"''${nixarr.stateDir}/audiobookshelf"'';
+      example = "/nixarr/.state/audiobookshelf";
+      description = ''
+        The location of the state directory for the Audiobookshelf service.
+
+        > **Warning:** Setting this to any path, where the subpath is not
+        > owned by root, will fail! For example:
+        >
+        > ```nix
+        >   stateDir = /home/user/nixarr/.state/audiobookshelf
+        > ```
+        >
+        > Is not supported, because `/home/user` is owned by `user`.
+      '';
+    };
+
+    port = mkOption {
+      type = types.port;
+      default = 9292;
+      example = 8000;
+      description = "Default port for Audiobookshelf";
+    };
+
+    openFirewall = mkOption {
+      type = types.bool;
+      defaultText = literalExpression ''!nixarr.audiobookshelf.vpn.enable'';
+      default = !cfg.vpn.enable;
+      example = true;
+      description = "Open firewall for Audiobookshelf";
+    };
+
+    vpn.enable = mkOption {
+      type = types.bool;
+      default = false;
+      example = true;
+      description = ''
+        **Required options:** [`nixarr.vpn.enable`](#nixarr.vpn.enable)
+
+        **Conflicting options:** [`nixarr.audiobookshelf.expose.https.enable`](#nixarr.audiobookshelf.expose.https.enable)
+
+        Route Audiobookshelf traffic through the VPN.
+      '';
+    };
+
+    expose = {
+      https = {
+        enable = mkOption {
+          type = types.bool;
+          default = false;
+          example = true;
+          description = ''
+            **Required options:**
+
+            - [`nixarr.audiobookshelf.expose.https.acmeMail`](#nixarr.audiobookshelf.expose.https.acmemail)
+            - [`nixarr.audiobookshelf.expose.https.domainName`](#nixarr.audiobookshelf.expose.https.domainname)
+
+            **Conflicting options:** [`nixarr.audiobookshelf.vpn.enable`](#nixarr.audiobookshelf.vpn.enable)
+
+            Expose the Audiobookshelf web service to the internet with https support,
+            allowing anyone to access it.
+
+            > **Warning:** Do _not_ enable this without setting up Audiobookshelf
+            > authentication through localhost first!
+          '';
+        };
+
+        upnp.enable = mkEnableOption "UPNP to try to open ports 80 and 443 on your router.";
+
+        domainName = mkOption {
+          type = types.nullOr types.str;
+          default = null;
+          example = "audiobookshelf.example.com";
+          description = "The domain name to host Audiobookshelf on.";
+        };
+
+        acmeMail = mkOption {
+          type = types.nullOr types.str;
+          default = null;
+          example = "mail@example.com";
+          description = "The ACME mail required for the letsencrypt bot.";
+        };
+      };
+    };
+  };
+
+  config = mkIf (nixarr.enable && cfg.enable) {
+    assertions = [
+      {
+        assertion = cfg.vpn.enable -> nixarr.vpn.enable;
+        message = ''
+          The nixarr.audiobookshelf.vpn.enable option requires the
+          nixarr.vpn.enable option to be set, but it was not.
+        '';
+      }
+      {
+        assertion = !(cfg.vpn.enable && cfg.expose.https.enable);
+        message = ''
+          The nixarr.audiobookshelf.vpn.enable option conflicts with the
+          nixarr.audiobookshelf.expose.https.enable option. You cannot set both.
+        '';
+      }
+      {
+        assertion =
+          cfg.expose.https.enable
+          -> (
+            (cfg.expose.https.domainName != null)
+            && (cfg.expose.https.acmeMail != null)
+          );
+        message = ''
+          The nixarr.audiobookshelf.expose.https.enable option requires the
+          following options to be set, but one of them were not:
+
+          - nixarr.audiobookshelf.expose.domainName
+          - nixarr.audiobookshelf.expose.acmeMail
+        '';
+      }
+    ];
+
+    users = {
+      groups.streamer = {};
+      users.streamer = {
+        isSystemUser = true;
+        group = "streamer";
+      };
+    };
+
+    systemd.tmpfiles.rules = [
+      "d '${cfg.stateDir}' 0700 streamer root - -"
+
+      # Media Dirs
+      "d '${nixarr.mediaDir}/library/books'    0775 streamer media - -"
+      "d '${nixarr.mediaDir}/library/podcasts' 0775 streamer media - -"
+    ];
+
+    # Always prioritise Audiobookshelf IO
+    systemd.services.audiobookshelf.serviceConfig.IOSchedulingPriority = 0;
+
+    services.audiobookshelf = {
+      enable = cfg.enable;
+      package = cfg.package;
+      port = cfg.port;
+      user = "streamer";
+      group = "media";
+      openFirewall = cfg.openFirewall;
+      dataDir = cfg.stateDir;
+    };
+
+    networking.firewall = mkIf cfg.expose.https.enable {
+      allowedTCPPorts = [80 443];
+    };
+
+    util-nixarr.upnp = mkIf cfg.expose.https.upnp.enable {
+      enable = true;
+      openTcpPorts = [80 443];
+    };
+
+    services.nginx = mkMerge [
+      (mkIf (cfg.expose.https.enable || cfg.vpn.enable) {
+        enable = true;
+
+        recommendedTlsSettings = true;
+        recommendedOptimisation = true;
+        recommendedGzipSettings = true;
+      })
+      (mkIf cfg.expose.https.enable {
+        virtualHosts."${builtins.replaceStrings ["\n"] [""] cfg.expose.https.domainName}" = {
+          enableACME = true;
+          forceSSL = true;
+          locations."/" = {
+            recommendedProxySettings = true;
+            proxyWebsockets = true;
+            proxyPass = "http://127.0.0.1:${builtins.toString cfg.port}";
+          };
+        };
+      })
+      (mkIf cfg.vpn.enable {
+        virtualHosts."127.0.0.1:${builtins.toString cfg.port}" = mkIf cfg.vpn.enable {
+          listen = [
+            {
+              addr = "0.0.0.0";
+              port = cfg.port;
+            }
+          ];
+          locations."/" = {
+            recommendedProxySettings = true;
+            proxyWebsockets = true;
+            proxyPass = "http://192.168.15.1:${builtins.toString cfg.port}";
+          };
+        };
+      })
+    ];
+
+    security.acme = mkIf cfg.expose.https.enable {
+      acceptTerms = true;
+      defaults.email = cfg.expose.https.acmeMail;
+    };
+
+    # Enable and specify VPN namespace to confine service in.
+    systemd.services.audiobookshelf.vpnConfinement = mkIf cfg.vpn.enable {
+      enable = true;
+      vpnNamespace = "wg";
+    };
+
+    # Port mappings
+    vpnNamespaces.wg = mkIf cfg.vpn.enable {
+      portMappings = [
+        {
+          from = cfg.port;
+          to = cfg.port;
+        }
+      ];
+    };
+  };
+}