diff --git a/grum/cli.py b/grum/cli.py
index e1df4ae..fb2d9b9 100644
--- a/grum/cli.py
+++ b/grum/cli.py
@@ -25,13 +25,14 @@ def handle_clargs():
     DESC = "grum - GUI for Remote Unified Monitoring"
     parser = argparse.ArgumentParser(description=DESC, formatter_class=argparse.ArgumentDefaultsHelpFormatter)
 
-    parser.add_argument("-H", "--host", default="localhost", help="Server host name")
-    parser.add_argument("-P", "--port", default=8000, type=int, help="Server port number")
+    parser.add_argument("-H", "--host", default="localhost", help="RPC server host name")
+    parser.add_argument("-P", "--port", default=8000, type=int, help="RPC server port number")
+    parser.add_argument("-o", "--offline", action="store_true", help="offline mode (do not run RPC server)")
 
-    parser.add_argument("-w", "--window-mode", default="multi", choices=MDIWindowMode.values(), type=unambiguous_window_mode, help="Set the initial window mode")
+    parser.add_argument("-w", "--window-mode", default="multi", choices=MDIWindowMode.values(), type=unambiguous_window_mode, help="set the initial window mode")
 
-    parser.add_argument("-e", "--examples", dest="add_examples", action="store_true", help="Add example data")
-    parser.add_argument("--no-theme", action="store_true", help="Disable theming")
+    parser.add_argument("-e", "--examples", dest="add_examples", action="store_true", help="add example data")
+    parser.add_argument("--no-theme", action="store_true", help="disable theming")
 
     return parser.parse_args().__dict__
 
diff --git a/grum/mainwin.py b/grum/mainwin.py
index cd7ed77..b15ea6b 100644
--- a/grum/mainwin.py
+++ b/grum/mainwin.py
@@ -18,8 +18,12 @@ class MainWindow(QMainWindow):
 
     sig_make_new_plot = pyqtSignal(str, PlotDescription)
 
-    def __init__(self, *args, title="grum", host="localhost", port=8000, add_examples=False, window_mode=MDIWindowMode.MULTI, **kwargs):
+    def __init__(self, *args, title="grum", host="localhost", port=8000, offline=False, add_examples=False, window_mode=MDIWindowMode.MULTI, **kwargs):
         super().__init__(*args, **kwargs)
+
+        if offline:
+            title = f"{title} (offline)"
+
         self.setWindowTitle(title)
         self.setWindowIcon(assets.icon())
 
@@ -62,10 +66,11 @@ class MainWindow(QMainWindow):
 
         self.setCentralWidget(splitter)
 
-        self.rst = rst = RPCServerThread(host, port, doc_title_suffix=title)
-        rst.start()
-        rst.server.register_function(self.new_plot)
-        rst.server.register_function(self.append_data)
+        if not offline:
+            self.rst = rst = RPCServerThread(host, port, doc_title_suffix=title)
+            rst.start()
+            rst.server.register_function(self.new_plot)
+            rst.server.register_function(self.append_data)
 
         self.sig_make_new_plot.connect(self.on_make_new_plot)