diff --git a/src/main/python/keyboard_comm.py b/src/main/python/keyboard_comm.py
index 4b26b10..bea5388 100644
--- a/src/main/python/keyboard_comm.py
+++ b/src/main/python/keyboard_comm.py
@@ -51,7 +51,7 @@ class Keyboard:
         self.layout = dict()
         self.encoder_layout = dict()
         self.rows = self.cols = self.layers = 0
-        self.layouts = None
+        self.layout_labels = None
         self.layout_options = -1
         self.keys = []
         self.encoders = []
@@ -112,7 +112,7 @@ class Keyboard:
             vial = payload["vial"]
             self.vibl = vial.get("vibl", False)
 
-        self.layouts = payload.get("layouts")
+        self.layout_labels = payload["layouts"].get("labels")
 
         self.rows = payload["matrix"]["rows"]
         self.cols = payload["matrix"]["cols"]
@@ -175,7 +175,7 @@ class Keyboard:
                 self.encoder_layout[(layer, idx, 0)] = struct.unpack(">H", data[0:2])[0]
                 self.encoder_layout[(layer, idx, 1)] = struct.unpack(">H", data[2:4])[0]
 
-        if self.layouts:
+        if self.layout_labels:
             data = self.usb_send(self.dev, struct.pack("BB", CMD_VIA_GET_KEYBOARD_VALUE, VIA_LAYOUT_OPTIONS),
                                  retries=20)
             self.layout_options = struct.unpack(">I", data[2:6])[0]
@@ -356,3 +356,71 @@ class Keyboard:
             return
 
         self.usb_send(self.dev, struct.pack("BB", CMD_VIA_VIAL_PREFIX, CMD_VIAL_LOCK), retries=20)
+
+
+class DummyKeyboard(Keyboard):
+
+    def reload_layers(self):
+        self.layers = 4
+
+    def reload_keymap(self):
+        for layer in range(self.layers):
+            for row, col in self.rowcol.keys():
+                self.layout[(layer, row, col)] = 0
+
+        for layer in range(self.layers):
+            for idx in self.encoderpos:
+                self.encoder_layout[(layer, idx, 0)] = 0
+                self.encoder_layout[(layer, idx, 1)] = 0
+
+        if self.layout_labels:
+            self.layout_options = 0
+
+    def reload_macros(self):
+        self.macro_count = 16
+        self.macro_memory = 900
+
+        self.macro = b"\x00" * self.macro_count
+
+    def set_key(self, layer, row, col, code):
+        if code < 0:
+            return
+        self.layout[(layer, row, col)] = code
+
+    def set_encoder(self, layer, index, direction, code):
+        if code < 0:
+            return
+        self.encoder_layout[(layer, index, direction)] = code
+
+    def set_layout_options(self, options):
+        if self.layout_options != -1 and self.layout_options != options:
+            self.layout_options = options
+
+    def set_macro(self, data):
+        if len(data) > self.macro_memory:
+            raise RuntimeError("the macro is too big: got {} max {}".format(len(data), self.macro_memory))
+        self.macro = data
+
+    def reset(self):
+        pass
+
+    def get_uid(self):
+        return b"\x00" * 8
+
+    def get_unlock_status(self):
+        return 1
+
+    def get_unlock_in_progress(self):
+        return 0
+
+    def get_unlock_keys(self):
+        return []
+
+    def unlock_start(self):
+        return
+
+    def unlock_poll(self):
+        return b""
+
+    def lock(self):
+        return
diff --git a/src/main/python/layout_editor.py b/src/main/python/layout_editor.py
index 7851c66..9473dea 100644
--- a/src/main/python/layout_editor.py
+++ b/src/main/python/layout_editor.py
@@ -112,7 +112,7 @@ class LayoutEditor(BasicEditor):
             choice.delete()
         self.choices = []
 
-        for item in device.keyboard.layouts["labels"]:
+        for item in device.keyboard.layout_labels:
             if isinstance(item, str):
                 choice = BooleanChoice(self.on_changed, self.container, item)
             else:
@@ -124,7 +124,7 @@ class LayoutEditor(BasicEditor):
         self.blockSignals(False)
 
     def valid(self):
-        return isinstance(self.device, VialKeyboard) and "labels" in self.device.keyboard.layouts
+        return isinstance(self.device, VialKeyboard) and self.device.keyboard.layout_labels
 
     def pack(self):
         if not self.choices:
diff --git a/src/main/python/main_window.py b/src/main/python/main_window.py
index 78e39a9..e26b647 100644
--- a/src/main/python/main_window.py
+++ b/src/main/python/main_window.py
@@ -96,6 +96,9 @@ class MainWindow(QMainWindow):
         download_via_stack_act = QAction(tr("MenuFile", "Download VIA definitions"), self)
         download_via_stack_act.triggered.connect(self.load_via_stack_json)
 
+        load_dummy_act = QAction(tr("MenuFile", "Load dummy JSON..."), self)
+        load_dummy_act.triggered.connect(self.on_load_dummy)
+
         exit_act = QAction(tr("MenuFile", "Exit"), self)
         exit_act.setShortcut("Ctrl+Q")
         exit_act.triggered.connect(qApp.exit)
@@ -106,6 +109,7 @@ class MainWindow(QMainWindow):
         file_menu.addSeparator()
         file_menu.addAction(sideload_json_act)
         file_menu.addAction(download_via_stack_act)
+        file_menu.addAction(load_dummy_act)
         file_menu.addSeparator()
         file_menu.addAction(exit_act)
 
@@ -243,6 +247,18 @@ class MainWindow(QMainWindow):
             self.sideload_pid = int(self.sideload_json["productId"], 16)
             self.on_click_refresh()
 
+    def on_load_dummy(self):
+        dialog = QFileDialog()
+        dialog.setDefaultSuffix("json")
+        dialog.setAcceptMode(QFileDialog.AcceptOpen)
+        dialog.setNameFilters(["VIA layout JSON (*.json)"])
+        if dialog.exec_() == QDialog.Accepted:
+            with open(dialog.selectedFiles()[0], "rb") as inf:
+                data = inf.read()
+            self.sideload_json = json.loads(data)
+            self.sideload_vid = self.sideload_pid = 0
+            self.on_click_refresh()
+
     def lock_ui(self):
         self.tabs.setEnabled(False)
         self.combobox_devices.setEnabled(False)
diff --git a/src/main/python/util.py b/src/main/python/util.py
index f22b40b..ed23ae6 100644
--- a/src/main/python/util.py
+++ b/src/main/python/util.py
@@ -53,7 +53,7 @@ def is_rawhid(dev):
 
 
 def find_vial_devices(via_stack_json, sideload_vid=None, sideload_pid=None):
-    from vial_device import VialBootloader, VialKeyboard
+    from vial_device import VialBootloader, VialKeyboard, VialDummyKeyboard
 
     filtered = []
     for dev in hid.enumerate():
@@ -66,6 +66,9 @@ def find_vial_devices(via_stack_json, sideload_vid=None, sideload_pid=None):
         elif str(dev["vendor_id"] * 65536 + dev["product_id"]) in via_stack_json["definitions"] and is_rawhid(dev):
             filtered.append(VialKeyboard(dev, via_stack=True))
 
+    if sideload_vid == sideload_pid == 0:
+        filtered.append(VialDummyKeyboard())
+
     return filtered
 
 
diff --git a/src/main/python/vial_device.py b/src/main/python/vial_device.py
index 83cc1b9..318f447 100644
--- a/src/main/python/vial_device.py
+++ b/src/main/python/vial_device.py
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 from hidproxy import hid
-from keyboard_comm import Keyboard
+from keyboard_comm import Keyboard, DummyKeyboard
 from util import MSG_LEN, pad_for_vibl
 
 
@@ -74,3 +74,22 @@ class VialBootloader(VialDevice):
         data = self.recv(8, timeout_ms=500)
         super().close()
         return data
+
+
+class VialDummyKeyboard(VialKeyboard):
+
+    def __init__(self):
+        self.sideload = True
+
+    def open(self, override_json=None):
+        self.keyboard = DummyKeyboard(None, usb_send=self.raise_usb_send)
+        self.keyboard.reload(override_json)
+
+    def title(self):
+        return "[Dummy Keyboard]"
+
+    def raise_usb_send(self, *args, **kwargs):
+        raise RuntimeError("usb_send - should not be called!")
+
+    def close(self):
+        pass