diff --git a/doc/plugin/LEDEffect-Breathe.md b/doc/plugin/LEDEffect-Breathe.md
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+# Kaleidoscope-LEDEffect-Breathe
+
+Provides a breathing effect for the keyboard. Breathe in, breathe out.
+
+## Using the extension
+
+To use the plugin, include the header, and tell the firmware to use it:
+
+```c++
+#include <Kaleidoscope-LEDControl.h>
+#include <Kaleidoscope-LEDEffect-Breathe.h>
+
+KALEIDOSCOPE_INIT_PLUGINS(LEDControl,
+                          LEDBreatheEffect);
+
+void setup() {
+  Kaleidoscope.setup();
+}
+```
+
+## Plugin properties
+
+The plugin provides the `LEDBreatheEffect` object, which has a single property:
+
+### `.hue`
+
+> The hue of the breathe effect.
+>
+> Defaults to 170, a blue hue.
+
+### `.saturation`
+
+> The color saturation of the breathe effect.
+>
+> Defaults to 255, the maximum.
+
+## Dependencies
+
+* [Kaleidoscope-LEDControl](LEDControl.md)
diff --git a/src/Kaleidoscope-LEDEffect-Breathe.h b/src/Kaleidoscope-LEDEffect-Breathe.h
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+/* Kaleidoscope-LEDEffect-Breathe - A breathing effect on the LEDs, for Kaleidoscope.
+ * Copyright (C) 2017-2018  Keyboard.io, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "kaleidoscope/plugin/LEDEffect-Breathe.h"
diff --git a/src/kaleidoscope/plugin/LEDEffect-Breathe.cpp b/src/kaleidoscope/plugin/LEDEffect-Breathe.cpp
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+++ b/src/kaleidoscope/plugin/LEDEffect-Breathe.cpp
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+/* Kaleidoscope-LEDEffect-Breathe - A breathing effect on the LEDs, for Kaleidoscope.
+ * Copyright (C) 2017-2018  Keyboard.io, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "Kaleidoscope-LEDEffect-Breathe.h"
+
+#define UPDATE_INTERVAL 50  // milliseconds between two LED updates to avoid overloading; 20 fps
+
+namespace kaleidoscope {
+namespace plugin {
+void LEDBreatheEffect::update(void) {
+  uint16_t now = Kaleidoscope.millisAtCycleStart();
+  if ((now - last_update_) < UPDATE_INTERVAL)
+    return;
+  last_update_ = now;
+
+  cRGB color = breath_compute(hue, saturation);
+  ::LEDControl.set_all_leds_to(color);
+}
+}
+}
+
+kaleidoscope::plugin::LEDBreatheEffect LEDBreatheEffect;
diff --git a/src/kaleidoscope/plugin/LEDEffect-Breathe.h b/src/kaleidoscope/plugin/LEDEffect-Breathe.h
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index 00000000..ade1e7dc
--- /dev/null
+++ b/src/kaleidoscope/plugin/LEDEffect-Breathe.h
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+/* Kaleidoscope-LEDEffect-Breathe - A breathing effect on the LEDs, for Kaleidoscope.
+ * Copyright (C) 2017-2018  Keyboard.io, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "Kaleidoscope-LEDControl.h"
+
+namespace kaleidoscope {
+namespace plugin {
+class LEDBreatheEffect : public LEDMode {
+ public:
+  LEDBreatheEffect(void) {}
+
+  uint8_t hue = 170;
+  uint8_t saturation = 255;
+
+ protected:
+  void update(void) final;
+
+ private:
+  uint16_t last_update_ = 0;
+};
+}
+}
+
+extern kaleidoscope::plugin::LEDBreatheEffect LEDBreatheEffect;