diff --git a/keyboards/drop/cstm80/board.h b/keyboards/drop/cstm80/board.h
new file mode 100644
index 000000000000..ed3ea4b1f776
--- /dev/null
+++ b/keyboards/drop/cstm80/board.h
@@ -0,0 +1,8 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#include_next <board.h>
+
+#undef STM32_HSECLK
+#define STM32_HSECLK 16000000U
diff --git a/keyboards/drop/cstm80/config.h b/keyboards/drop/cstm80/config.h
new file mode 100644
index 000000000000..2aefadfe303d
--- /dev/null
+++ b/keyboards/drop/cstm80/config.h
@@ -0,0 +1,22 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#define I2C1_SCL_PIN B8
+#define I2C1_SDA_PIN B9
+
+#define EXTERNAL_EEPROM_I2C_BASE_ADDRESS 0b10101000
+#define EXTERNAL_EEPROM_WP_PIN B7
+#define EEPROM_I2C_24LC256
+
+#define DRIVER_ADDR_1 0b1010000
+#define DRIVER_ADDR_2 0b1011111
+#define DRIVER_COUNT 2
+#define RGB_MATRIX_LED_COUNT 88
+#define ISSI_PWM_FREQUENCY 0b010 // 26k
+
+#define RGB_DISABLE_WHEN_USB_SUSPENDED
+#define RGB_MATRIX_KEYPRESSES
+#define RGB_MATRIX_FRAMEBUFFER_EFFECTS
+
+#define RGB_MATRIX_CAPS_LOCK_INDEX 48
diff --git a/keyboards/drop/cstm80/cstm80.c b/keyboards/drop/cstm80/cstm80.c
new file mode 100644
index 000000000000..c60f347cb9b7
--- /dev/null
+++ b/keyboards/drop/cstm80/cstm80.c
@@ -0,0 +1,96 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#ifdef RGB_MATRIX_ENABLE
+#    include "rgb_matrix.h"
+
+const is31_led PROGMEM g_is31_leds[RGB_MATRIX_LED_COUNT] = {
+    { 0, E_1,  D_1,  F_1  },
+    { 0, E_2,  D_2,  F_2  },
+    { 0, E_3,  D_3,  F_3  },
+    { 0, E_4,  D_4,  F_4  },
+    { 0, E_5,  D_5,  F_5  },
+    { 0, E_6,  D_6,  F_6  },
+    { 0, E_7,  D_7,  F_7  },
+    { 0, E_8,  D_8,  F_8  },
+    { 0, E_9,  D_9,  F_9  },
+    { 0, E_10, D_10, F_10 },
+    { 0, E_11, D_11, F_11 },
+    { 0, E_12, D_12, F_12 },
+    { 0, E_13, D_13, F_13 },
+    { 0, E_14, D_14, F_14 },
+    { 0, E_15, D_15, F_15 },
+    { 0, E_16, D_16, F_16 },
+    { 0, H_1,  G_1,  I_1  },
+    { 0, H_2,  G_2,  I_2  },
+    { 0, H_3,  G_3,  I_3  },
+    { 0, H_4,  G_4,  I_4  },
+    { 0, H_5,  G_5,  I_5  },
+    { 0, H_6,  G_6,  I_6  },
+    { 0, H_7,  G_7,  I_7  },
+    { 0, H_8,  G_8,  I_8  },
+    { 0, H_9,  G_9,  I_9  },
+    { 0, H_10, G_10, I_10 },
+    { 0, H_11, G_11, I_11 },
+    { 0, H_12, G_12, I_12 },
+    { 0, H_13, G_13, I_13 },
+    { 0, H_14, G_14, I_14 },
+    { 0, H_15, G_15, I_15 },
+    { 0, H_16, G_16, I_16 },
+    { 0, K_1,  J_1,  L_1  },
+    { 0, K_2,  J_2,  L_2  },
+    { 0, K_3,  J_3,  L_3  },
+    { 0, K_4,  J_4,  L_4  },
+    { 0, K_5,  J_5,  L_5  },
+    { 0, K_6,  J_6,  L_6  },
+    { 0, K_7,  J_7,  L_7  },
+    { 0, K_8,  J_8,  L_8  },
+    { 0, K_9,  J_9,  L_9  },
+    { 0, K_10, J_10, L_10 },
+    { 0, K_11, J_11, L_11 },
+    { 0, K_12, J_12, L_12 },
+    { 0, K_13, J_13, L_13 },
+    { 0, K_14, J_14, L_14 },
+    { 0, K_15, J_15, L_15 },
+    { 0, K_16, J_16, L_16 },
+    { 1, B_1,  A_1,  C_1  },
+    { 1, B_2,  A_2,  C_2  },
+    { 1, B_3,  A_3,  C_3  },
+    { 1, B_4,  A_4,  C_4  },
+    { 1, B_5,  A_5,  C_5  },
+    { 1, B_6,  A_6,  C_6  },
+    { 1, B_7,  A_7,  C_7  },
+    { 1, B_8,  A_8,  C_8  },
+    { 1, B_9,  A_9,  C_9  },
+    { 1, B_10, A_10, C_10 },
+    { 1, B_11, A_11, C_11 },
+    { 1, B_12, A_12, C_12 },
+    { 1, B_13, A_13, C_13 },
+    { 1, B_14, A_14, C_14 },
+    { 1, B_15, A_15, C_15 },
+    { 1, B_16, A_16, C_16 },
+    { 1, E_1,  D_1,  F_1  },
+    { 1, E_2,  D_2,  F_2  },
+    { 1, E_3,  D_3,  F_3  },
+    { 1, E_4,  D_4,  F_4  },
+    { 1, E_5,  D_5,  F_5  },
+    { 1, E_6,  D_6,  F_6  },
+    { 1, E_7,  D_7,  F_7  },
+    { 1, E_8,  D_8,  F_8  },
+    { 1, E_9,  D_9,  F_9  },
+    { 1, E_10, D_10, F_10 },
+    { 1, E_11, D_11, F_11 },
+    { 1, E_12, D_12, F_12 },
+    { 1, E_13, D_13, F_13 },
+    { 1, H_1,  G_1,  I_1  },
+    { 1, H_2,  G_2,  I_2  },
+    { 1, H_3,  G_3,  I_3  },
+    { 1, H_4,  G_4,  I_4  },
+    { 1, H_5,  G_5,  I_5  },
+    { 1, H_6,  G_6,  I_6  },
+    { 1, H_7,  G_7,  I_7  },
+    { 1, H_8,  G_8,  I_8  },
+    { 1, H_9,  G_9,  I_9  },
+    { 1, H_10, G_10, I_10 },
+    { 1, H_11, G_11, I_11 },
+};
+#endif
diff --git a/keyboards/drop/cstm80/halconf.h b/keyboards/drop/cstm80/halconf.h
new file mode 100644
index 000000000000..2677c2a654c8
--- /dev/null
+++ b/keyboards/drop/cstm80/halconf.h
@@ -0,0 +1,7 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#define HAL_USE_I2C TRUE
+
+#include_next <halconf.h>
diff --git a/keyboards/drop/cstm80/info.json b/keyboards/drop/cstm80/info.json
new file mode 100644
index 000000000000..170538027e41
--- /dev/null
+++ b/keyboards/drop/cstm80/info.json
@@ -0,0 +1,272 @@
+{
+    "keyboard_name": "CSTM80",
+    "manufacturer": "Drop Inc.",
+    "maintainer": "zvecr",
+    "processor": "STM32F303",
+    "bootloader": "tinyuf2",
+    "diode_direction": "COL2ROW",
+    "matrix_pins": {
+        "cols": ["C15", "C14", "C13", "C12", "C11", "C10", "C9", "C8", "C7", "C6", "C5", "C4", "C3", "C2", "C1", "C0", "D2"],
+        "rows": ["B15", "B14", "B13", "B12", "B11", "B10"]
+    },
+    "usb": {
+        "vid": "0x359B",
+        "pid": "0x0004",
+        "device_version": "1.0.0"
+    },
+    "eeprom": {
+        "driver": "i2c"
+    },
+    "features": {
+        "rgb_matrix": true,
+        "bootmagic": true,
+        "command": false,
+        "console": false,
+        "extrakey": true,
+        "mousekey": true,
+        "nkro": true
+    },
+    "community_layouts": ["tkl_f13_ansi"],
+    "layouts": {
+        "LAYOUT_tkl_f13_ansi": {
+            "layout": [
+                { "matrix": [0,  0], "label":"Esc",   "x":0, "y":0},
+                { "matrix": [0,  1], "label":"F1",    "x":1.25, "y":0},
+                { "matrix": [0,  2], "label":"F2",    "x":2.25, "y":0},
+                { "matrix": [0,  3], "label":"F3",    "x":3.25, "y":0},
+                { "matrix": [0,  4], "label":"F4",    "x":4.25, "y":0},
+                { "matrix": [0,  5], "label":"F5",    "x":5.5, "y":0},
+                { "matrix": [0,  6], "label":"F6",    "x":6.5, "y":0},
+                { "matrix": [0,  7], "label":"F7",    "x":7.5, "y":0},
+                { "matrix": [0,  8], "label":"F8",    "x":8.5, "y":0},
+                { "matrix": [0,  9], "label":"F9",    "x":9.75, "y":0},
+                { "matrix": [0, 10], "label":"F10",   "x":10.75, "y":0},
+                { "matrix": [0, 11], "label":"F11",   "x":11.75, "y":0},
+                { "matrix": [0, 12], "label":"F12",   "x":12.75, "y":0},
+                { "matrix": [0, 13], "label":"F13",   "x":14, "y":0},
+                { "matrix": [0, 14], "label":"PrtSc", "x":15.25, "y":0},
+                { "matrix": [0, 15], "label":"ScrLk", "x":16.25, "y":0},
+                { "matrix": [0, 16], "label":"Pause", "x":17.25, "y":0},
+
+                { "matrix": [1,  0], "label":"~",      "x":0, "y":1.25},
+                { "matrix": [1,  1], "label":"!",      "x":1, "y":1.25},
+                { "matrix": [1,  2], "label":"@",      "x":2, "y":1.25},
+                { "matrix": [1,  3], "label":"#",      "x":3, "y":1.25},
+                { "matrix": [1,  4], "label":"$",      "x":4, "y":1.25},
+                { "matrix": [1,  5], "label":"%",      "x":5, "y":1.25},
+                { "matrix": [1,  6], "label":"^",      "x":6, "y":1.25},
+                { "matrix": [1,  7], "label":"&",      "x":7, "y":1.25},
+                { "matrix": [1,  8], "label":"*",      "x":8, "y":1.25},
+                { "matrix": [1,  9], "label":"(",      "x":9, "y":1.25},
+                { "matrix": [1, 10], "label":")",      "x":10, "y":1.25},
+                { "matrix": [1, 11], "label":"_",      "x":11, "y":1.25},
+                { "matrix": [1, 12], "label":"+",      "x":12, "y":1.25},
+                { "matrix": [1, 13], "label":"Bksp",   "x":13, "y":1.25, "w":2},
+                { "matrix": [1, 14], "label":"Insert", "x":15.25, "y":1.25},
+                { "matrix": [1, 15], "label":"Home",   "x":16.25, "y":1.25},
+                { "matrix": [1, 16], "label":"Page Up", "x":17.25, "y":1.25},
+
+                { "matrix": [2,  0], "label":"Tab",     "x":0, "y":2.25, "w":1.5},
+                { "matrix": [2,  1], "label":"Q",       "x":1.5, "y":2.25},
+                { "matrix": [2,  2], "label":"W",       "x":2.5, "y":2.25},
+                { "matrix": [2,  3], "label":"E",       "x":3.5, "y":2.25},
+                { "matrix": [2,  4], "label":"R",       "x":4.5, "y":2.25},
+                { "matrix": [2,  5], "label":"T",       "x":5.5, "y":2.25},
+                { "matrix": [2,  6], "label":"Y",       "x":6.5, "y":2.25},
+                { "matrix": [2,  7], "label":"U",       "x":7.5, "y":2.25},
+                { "matrix": [2,  8], "label":"I",       "x":8.5, "y":2.25},
+                { "matrix": [2,  9], "label":"O",       "x":9.5, "y":2.25},
+                { "matrix": [2, 10], "label":"P",       "x":10.5, "y":2.25},
+                { "matrix": [2, 11], "label":"{",       "x":11.5, "y":2.25},
+                { "matrix": [2, 12], "label":"}",       "x":12.5, "y":2.25},
+                { "matrix": [2, 13], "label":"|",       "x":13.5, "y":2.25, "w":1.5},
+                { "matrix": [2, 14], "label":"Delete",  "x":15.25, "y":2.25},
+                { "matrix": [2, 15], "label":"End",     "x":16.25, "y":2.25},
+                { "matrix": [2, 16], "label":"Page Dn", "x":17.25, "y":2.25},
+
+                { "matrix": [3,  0], "label":"CapsLk", "x":0, "y":3.25, "w":1.75},
+                { "matrix": [3,  1], "label":"A",      "x":1.75, "y":3.25},
+                { "matrix": [3,  2], "label":"S",      "x":2.75, "y":3.25},
+                { "matrix": [3,  3], "label":"D",      "x":3.75, "y":3.25},
+                { "matrix": [3,  4], "label":"F",      "x":4.75, "y":3.25},
+                { "matrix": [3,  5], "label":"G",      "x":5.75, "y":3.25},
+                { "matrix": [3,  6], "label":"H",      "x":6.75, "y":3.25},
+                { "matrix": [3,  7], "label":"J",      "x":7.75, "y":3.25},
+                { "matrix": [3,  8], "label":"K",      "x":8.75, "y":3.25},
+                { "matrix": [3,  9], "label":"L",      "x":9.75, "y":3.25},
+                { "matrix": [3, 10], "label":":",      "x":10.75, "y":3.25},
+                { "matrix": [3, 11], "label":"\"",     "x":11.75, "y":3.25},
+                { "matrix": [3, 13], "label":"Enter",  "x":12.75, "y":3.25, "w":2.25},
+
+                { "matrix": [4,  0], "label":"Shift",  "x":0, "y":4.25, "w":2.25},
+                { "matrix": [4,  1], "label":"Z",      "x":2.25, "y":4.25},
+                { "matrix": [4,  2], "label":"X",      "x":3.25, "y":4.25},
+                { "matrix": [4,  3], "label":"C",      "x":4.25, "y":4.25},
+                { "matrix": [4,  4], "label":"V",      "x":5.25, "y":4.25},
+                { "matrix": [4,  5], "label":"B",      "x":6.25, "y":4.25},
+                { "matrix": [4,  6], "label":"N",      "x":7.25, "y":4.25},
+                { "matrix": [4,  7], "label":"M",      "x":8.25, "y":4.25},
+                { "matrix": [4,  8], "label":"<",      "x":9.25, "y":4.25},
+                { "matrix": [4,  9], "label":">",      "x":10.25, "y":4.25},
+                { "matrix": [4, 10], "label":"?",      "x":11.25, "y":4.25},
+                { "matrix": [4, 12], "label":"Shift",  "x":12.25, "y":4.25, "w":2.75},
+                { "matrix": [4, 15], "label":"\u2191", "x":16.25, "y":4.25},
+
+                { "matrix": [5,  0], "label":"Ctrl",   "x":0, "y":5.25, "w":1.25},
+                { "matrix": [5,  1], "label":"Win",    "x":1.25, "y":5.25, "w":1.25},
+                { "matrix": [5,  2], "label":"Alt",    "x":2.5, "y":5.25, "w":1.25},
+                { "matrix": [5,  6], "label":" ",      "x":3.75, "y":5.25, "w":6.25},
+                { "matrix": [5, 10], "label":"Alt",    "x":10, "y":5.25, "w":1.25},
+                { "matrix": [5, 11], "label":"Fn",     "x":11.25, "y":5.25, "w":1.25},
+                { "matrix": [5, 12], "label":"Menu",   "x":12.5, "y":5.25, "w":1.25},
+                { "matrix": [5, 13], "label":"Ctrl",   "x":13.75, "y":5.25, "w":1.25},
+                { "matrix": [5, 14], "label":"\u2190", "x":15.25, "y":5.25},
+                { "matrix": [5, 15], "label":"\u2193", "x":16.25, "y":5.25},
+                { "matrix": [5, 16], "label":"\u2192", "x":17.25, "y":5.25}
+            ]
+        }
+    },
+    "rgb_matrix": {
+        "driver": "is31fl3733",
+        "animations": {
+            "alphas_mods": true,
+            "gradient_up_down": true,
+            "gradient_left_right": true,
+            "breathing": true,
+            "band_sat": true,
+            "band_val": true,
+            "band_pinwheel_sat": true,
+            "band_pinwheel_val": true,
+            "band_spiral_sat": true,
+            "band_spiral_val": true,
+            "cycle_all": true,
+            "cycle_left_right": true,
+            "cycle_up_down": true,
+            "cycle_out_in": true,
+            "cycle_out_in_dual": true,
+            "rainbow_moving_chevron": true,
+            "cycle_pinwheel": true,
+            "cycle_spiral": true,
+            "dual_beacon": true,
+            "rainbow_beacon": true,
+            "rainbow_pinwheels": true,
+            "raindrops": true,
+            "jellybean_raindrops": true,
+            "hue_breathing": true,
+            "hue_pendulum": true,
+            "hue_wave": true,
+            "pixel_fractal": true,
+            "pixel_flow": true,
+            "pixel_rain": true,
+            "typing_heatmap": true,
+            "digital_rain": true,
+            "solid_reactive_simple": true,
+            "solid_reactive": true,
+            "solid_reactive_wide": true,
+            "solid_reactive_multiwide": true,
+            "solid_reactive_cross": true,
+            "solid_reactive_multicross": true,
+            "solid_reactive_nexus": true,
+            "solid_reactive_multinexus": true,
+            "splash": true,
+            "multisplash": true,
+            "solid_splash": true,
+            "solid_multisplash": true
+        },
+        "layout": [
+            { "flags": 4, "matrix": [0,  0], "x":   6, "y":  8 },
+            { "flags": 4, "matrix": [0,  1], "x":  21, "y":  8 },
+            { "flags": 4, "matrix": [0,  2], "x":  33, "y":  8 },
+            { "flags": 4, "matrix": [0,  3], "x":  45, "y":  8 },
+            { "flags": 4, "matrix": [0,  4], "x":  57, "y":  8 },
+            { "flags": 4, "matrix": [0,  5], "x":  74, "y":  8 },
+            { "flags": 4, "matrix": [0,  6], "x":  86, "y":  8 },
+            { "flags": 4, "matrix": [0,  7], "x":  98, "y":  8 },
+            { "flags": 4, "matrix": [0,  8], "x": 110, "y":  8 },
+            { "flags": 4, "matrix": [0,  9], "x": 125, "y":  8 },
+            { "flags": 4, "matrix": [0, 10], "x": 137, "y":  8 },
+            { "flags": 4, "matrix": [0, 11], "x": 150, "y":  8 },
+            { "flags": 4, "matrix": [0, 12], "x": 161, "y":  8 },
+            { "flags": 4, "matrix": [0, 13], "x": 176, "y":  8 },
+            { "flags": 4, "matrix": [0, 14], "x": 192, "y":  8 },
+            { "flags": 4, "matrix": [0, 15], "x": 204, "y":  8 },
+
+            { "flags": 4, "matrix": [1,  0], "x":   6, "y": 21 },
+            { "flags": 4, "matrix": [1,  1], "x":  18, "y": 21 },
+            { "flags": 4, "matrix": [1,  2], "x":  37, "y": 21 },
+            { "flags": 4, "matrix": [1,  3], "x":  43, "y": 21 },
+            { "flags": 4, "matrix": [1,  4], "x":  55, "y": 21 },
+            { "flags": 4, "matrix": [1,  5], "x":  67, "y": 21 },
+            { "flags": 4, "matrix": [1,  6], "x":  79, "y": 21 },
+            { "flags": 4, "matrix": [1,  7], "x":  92, "y": 21 },
+            { "flags": 4, "matrix": [1,  8], "x": 104, "y": 21 },
+            { "flags": 4, "matrix": [1,  9], "x": 116, "y": 21 },
+            { "flags": 4, "matrix": [1, 10], "x": 128, "y": 21 },
+            { "flags": 4, "matrix": [1, 11], "x": 141, "y": 21 },
+            { "flags": 4, "matrix": [1, 12], "x": 153, "y": 21 },
+            { "flags": 4, "matrix": [1, 13], "x": 171, "y": 21 },
+            { "flags": 4, "matrix": [1, 14], "x": 192, "y": 21 },
+            { "flags": 4, "matrix": [1, 15], "x": 204, "y": 21 },
+
+            { "flags": 4, "matrix": [2,  0], "x":   9, "y": 31 },
+            { "flags": 4, "matrix": [2,  1], "x":  24, "y": 31 },
+            { "flags": 4, "matrix": [2,  2], "x":  36, "y": 31 },
+            { "flags": 4, "matrix": [2,  3], "x":  48, "y": 31 },
+            { "flags": 4, "matrix": [2,  4], "x":  61, "y": 31 },
+            { "flags": 4, "matrix": [2,  5], "x":  73, "y": 31 },
+            { "flags": 4, "matrix": [2,  6], "x":  86, "y": 31 },
+            { "flags": 4, "matrix": [2,  7], "x":  98, "y": 31 },
+            { "flags": 4, "matrix": [2,  8], "x": 110, "y": 31 },
+            { "flags": 4, "matrix": [2,  9], "x": 122, "y": 31 },
+            { "flags": 4, "matrix": [2, 10], "x": 134, "y": 31 },
+            { "flags": 4, "matrix": [2, 11], "x": 146, "y": 31 },
+            { "flags": 4, "matrix": [2, 12], "x": 159, "y": 31 },
+            { "flags": 4, "matrix": [2, 13], "x": 174, "y": 31 },
+            { "flags": 4, "matrix": [2, 14], "x": 192, "y": 31 },
+            { "flags": 4, "matrix": [2, 15], "x": 204, "y": 31 },
+
+            { "flags": 4, "matrix": [3,  0], "x":  11, "y": 41 },
+            { "flags": 4, "matrix": [3,  1], "x":  27, "y": 41 },
+            { "flags": 4, "matrix": [3,  2], "x":  40, "y": 41 },
+            { "flags": 4, "matrix": [3,  3], "x":  52, "y": 41 },
+            { "flags": 4, "matrix": [3,  4], "x":  64, "y": 41 },
+            { "flags": 4, "matrix": [3,  5], "x":  76, "y": 41 },
+            { "flags": 4, "matrix": [3,  6], "x":  88, "y": 41 },
+            { "flags": 4, "matrix": [3,  7], "x": 100, "y": 41 },
+            { "flags": 4, "matrix": [3,  8], "x": 113, "y": 41 },
+            { "flags": 4, "matrix": [3,  9], "x": 124, "y": 41 },
+            { "flags": 4, "matrix": [3, 10], "x": 137, "y": 41 },
+            { "flags": 4, "matrix": [3, 11], "x": 150, "y": 41 },
+            { "flags": 4, "matrix": [3, 12], "x": 170, "y": 41 },
+            { "flags": 4, "matrix": [0, 16], "x": 217, "y":  8 },
+            { "flags": 4, "matrix": [1, 16], "x": 217, "y": 21 },
+            { "flags": 4, "matrix": [2, 16], "x": 217, "y": 31 },
+
+            { "flags": 4, "matrix": [4,  0], "x":  13, "y": 51 },
+            { "flags": 4, "matrix": [4,  1], "x":  34, "y": 51 },
+            { "flags": 4, "matrix": [4,  2], "x":  45, "y": 51 },
+            { "flags": 4, "matrix": [4,  3], "x":  58, "y": 51 },
+            { "flags": 4, "matrix": [4,  4], "x":  70, "y": 51 },
+            { "flags": 4, "matrix": [4,  5], "x":  82, "y": 51 },
+            { "flags": 4, "matrix": [4,  6], "x":  94, "y": 51 },
+            { "flags": 4, "matrix": [4,  7], "x": 107, "y": 51 },
+            { "flags": 4, "matrix": [4,  8], "x": 119, "y": 51 },
+            { "flags": 4, "matrix": [4,  9], "x": 131, "y": 51 },
+            { "flags": 4, "matrix": [4, 10], "x": 143, "y": 51 },
+            { "flags": 4, "matrix": [4, 12], "x": 166, "y": 51 },
+            { "flags": 4, "matrix": [4, 15], "x": 204, "y": 51 },
+
+            { "flags": 4, "matrix": [5,  0], "x":   8, "y": 61 },
+            { "flags": 4, "matrix": [5,  1], "x":  23, "y": 61 },
+            { "flags": 4, "matrix": [5,  2], "x":  38, "y": 61 },
+            { "flags": 4, "matrix": [5,  6], "x":  84, "y": 61 },
+            { "flags": 4, "matrix": [5, 10], "x": 129, "y": 61 },
+            { "flags": 4, "matrix": [5, 11], "x": 144, "y": 61 },
+            { "flags": 4, "matrix": [5, 12], "x": 160, "y": 61 },
+            { "flags": 4, "matrix": [5, 13], "x": 175, "y": 61 },
+            { "flags": 4, "matrix": [5, 14], "x": 192, "y": 61 },
+            { "flags": 4, "matrix": [5, 15], "x": 204, "y": 61 },
+            { "flags": 4, "matrix": [5, 16], "x": 217, "y": 61 }
+        ]
+    }
+}
diff --git a/keyboards/drop/cstm80/keymaps/default/keymap.c b/keyboards/drop/cstm80/keymaps/default/keymap.c
new file mode 100644
index 000000000000..e820a0a74358
--- /dev/null
+++ b/keyboards/drop/cstm80/keymaps/default/keymap.c
@@ -0,0 +1,38 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include QMK_KEYBOARD_H
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+    /*
+     * ┌───┐┌───┬───┬───┬───┐┌───┬───┬───┬───┐┌───┬───┬───┬───┐┌───┐┌───┬───┬───┐
+     * │Esc││F1 │F2 │F3 │F4 ││F5 │F6 │F7 │F8 ││F9 │F10│F11│F12││F13││PSc│Scr│Pse│
+     * └───┘└───┴───┴───┴───┘└───┴───┴───┴───┘└───┴───┴───┴───┘└───┘└───┴───┴───┘
+     * ┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───────┐┌───┬───┬───┐
+     * │ ` │ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 7 │ 8 │ 9 │ 0 │ - │ = │ Backsp││Ins│Hom│PgU│
+     * ├───┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─────┤├───┼───┼───┤
+     * │ Tab │ Q │ W │ E │ R │ T │ Y │ U │ I │ O │ P │ [ │ ] │  \  ││Del│End│PgD│
+     * ├─────┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴─────┤└───┴───┴───┘
+     * │ Caps │ A │ S │ D │ F │ G │ H │ J │ K │ L │ ; │ ' │  Enter │
+     * ├──────┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴────────┤    ┌───┐
+     * │ Shift  │ Z │ X │ C │ V │ B │ N │ M │ , │ . │ / │    Shift │    │ ↑ │
+     * ├────┬───┴┬──┴─┬─┴───┴───┴───┴───┴───┴──┬┴───┼───┴┬────┬────┤┌───┼───┼───┐
+     * │Ctrl│GUI │Alt │                        │ Alt│ GUI│Menu│Ctrl││ ← │ ↓ │ → │
+     * └────┴────┴────┴────────────────────────┴────┴────┴────┴────┘└───┴───┴───┘
+     */
+    [0] = LAYOUT_tkl_f13_ansi(
+        KC_ESC,  KC_F1,   KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   KC_F7,   KC_F8,   KC_F9,   KC_F10,  KC_F11,  KC_F12,  KC_F13,     KC_PSCR, KC_SCRL, KC_PAUS,
+        KC_GRV,  KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,    KC_8,    KC_9,    KC_0,    KC_MINS, KC_EQL,  KC_BSPC,    KC_INS,  KC_HOME, KC_PGUP,
+        KC_TAB,  KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_LBRC, KC_RBRC, KC_BSLS,    KC_DEL,  KC_END,  KC_PGDN,
+        KC_CAPS, KC_A,    KC_S,    KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT,          KC_ENT,
+        KC_LSFT,          KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH,          KC_RSFT,             KC_UP,
+        KC_LCTL, KC_LGUI, KC_LALT,                            KC_SPC,                             KC_RALT, MO(1),   KC_APP,  KC_RCTL,    KC_LEFT, KC_DOWN, KC_RGHT
+    ),
+    [1] = LAYOUT_tkl_f13_ansi(
+        _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,    _______, _______, _______,
+        _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, QK_BOOT,    _______, _______, _______,
+        _______, RGB_TOG, RGB_VAI, RGB_SPI, RGB_HUI, RGB_SAI, _______, _______, _______, _______, _______, _______, _______, _______,    _______, _______, _______,
+        _______, RGB_MOD, RGB_VAD, RGB_SPD, RGB_HUD, RGB_SAD, _______, _______, _______, _______, _______, _______,          _______,
+        _______,          RGB_M_P, RGB_M_B, RGB_M_R, RGB_M_SW,_______, NK_TOGG, _______, _______, _______, _______,          _______,             _______,
+        _______, _______, _______,                            EE_CLR,                             _______, _______, _______, _______,    _______, _______, _______
+    )
+};
diff --git a/keyboards/drop/cstm80/keymaps/via/config.h b/keyboards/drop/cstm80/keymaps/via/config.h
new file mode 100644
index 000000000000..616f8e329102
--- /dev/null
+++ b/keyboards/drop/cstm80/keymaps/via/config.h
@@ -0,0 +1,5 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#define DYNAMIC_KEYMAP_LAYER_COUNT 8
diff --git a/keyboards/drop/cstm80/keymaps/via/keymap.c b/keyboards/drop/cstm80/keymaps/via/keymap.c
new file mode 100644
index 000000000000..e820a0a74358
--- /dev/null
+++ b/keyboards/drop/cstm80/keymaps/via/keymap.c
@@ -0,0 +1,38 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include QMK_KEYBOARD_H
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+    /*
+     * ┌───┐┌───┬───┬───┬───┐┌───┬───┬───┬───┐┌───┬───┬───┬───┐┌───┐┌───┬───┬───┐
+     * │Esc││F1 │F2 │F3 │F4 ││F5 │F6 │F7 │F8 ││F9 │F10│F11│F12││F13││PSc│Scr│Pse│
+     * └───┘└───┴───┴───┴───┘└───┴───┴───┴───┘└───┴───┴───┴───┘└───┘└───┴───┴───┘
+     * ┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───────┐┌───┬───┬───┐
+     * │ ` │ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 7 │ 8 │ 9 │ 0 │ - │ = │ Backsp││Ins│Hom│PgU│
+     * ├───┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─────┤├───┼───┼───┤
+     * │ Tab │ Q │ W │ E │ R │ T │ Y │ U │ I │ O │ P │ [ │ ] │  \  ││Del│End│PgD│
+     * ├─────┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴┬──┴─────┤└───┴───┴───┘
+     * │ Caps │ A │ S │ D │ F │ G │ H │ J │ K │ L │ ; │ ' │  Enter │
+     * ├──────┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴─┬─┴────────┤    ┌───┐
+     * │ Shift  │ Z │ X │ C │ V │ B │ N │ M │ , │ . │ / │    Shift │    │ ↑ │
+     * ├────┬───┴┬──┴─┬─┴───┴───┴───┴───┴───┴──┬┴───┼───┴┬────┬────┤┌───┼───┼───┐
+     * │Ctrl│GUI │Alt │                        │ Alt│ GUI│Menu│Ctrl││ ← │ ↓ │ → │
+     * └────┴────┴────┴────────────────────────┴────┴────┴────┴────┘└───┴───┴───┘
+     */
+    [0] = LAYOUT_tkl_f13_ansi(
+        KC_ESC,  KC_F1,   KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   KC_F7,   KC_F8,   KC_F9,   KC_F10,  KC_F11,  KC_F12,  KC_F13,     KC_PSCR, KC_SCRL, KC_PAUS,
+        KC_GRV,  KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,    KC_8,    KC_9,    KC_0,    KC_MINS, KC_EQL,  KC_BSPC,    KC_INS,  KC_HOME, KC_PGUP,
+        KC_TAB,  KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_LBRC, KC_RBRC, KC_BSLS,    KC_DEL,  KC_END,  KC_PGDN,
+        KC_CAPS, KC_A,    KC_S,    KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT,          KC_ENT,
+        KC_LSFT,          KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH,          KC_RSFT,             KC_UP,
+        KC_LCTL, KC_LGUI, KC_LALT,                            KC_SPC,                             KC_RALT, MO(1),   KC_APP,  KC_RCTL,    KC_LEFT, KC_DOWN, KC_RGHT
+    ),
+    [1] = LAYOUT_tkl_f13_ansi(
+        _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,    _______, _______, _______,
+        _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, QK_BOOT,    _______, _______, _______,
+        _______, RGB_TOG, RGB_VAI, RGB_SPI, RGB_HUI, RGB_SAI, _______, _______, _______, _______, _______, _______, _______, _______,    _______, _______, _______,
+        _______, RGB_MOD, RGB_VAD, RGB_SPD, RGB_HUD, RGB_SAD, _______, _______, _______, _______, _______, _______,          _______,
+        _______,          RGB_M_P, RGB_M_B, RGB_M_R, RGB_M_SW,_______, NK_TOGG, _______, _______, _______, _______,          _______,             _______,
+        _______, _______, _______,                            EE_CLR,                             _______, _______, _______, _______,    _______, _______, _______
+    )
+};
diff --git a/keyboards/drop/cstm80/keymaps/via/rules.mk b/keyboards/drop/cstm80/keymaps/via/rules.mk
new file mode 100644
index 000000000000..1e5b99807cb7
--- /dev/null
+++ b/keyboards/drop/cstm80/keymaps/via/rules.mk
@@ -0,0 +1 @@
+VIA_ENABLE = yes
diff --git a/keyboards/drop/cstm80/mcuconf.h b/keyboards/drop/cstm80/mcuconf.h
new file mode 100644
index 000000000000..819aa70bf7fa
--- /dev/null
+++ b/keyboards/drop/cstm80/mcuconf.h
@@ -0,0 +1,14 @@
+// Copyright 2023 Massdrop, Inc.
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#include_next <mcuconf.h>
+
+#undef STM32_PLLM_VALUE
+#define STM32_PLLM_VALUE 16
+
+#undef STM32_PREDIV_VALUE
+#define STM32_PREDIV_VALUE 2
+
+#undef STM32_I2C_USE_I2C1
+#define STM32_I2C_USE_I2C1 TRUE
diff --git a/keyboards/drop/cstm80/readme.md b/keyboards/drop/cstm80/readme.md
new file mode 100644
index 000000000000..f0851cc045bf
--- /dev/null
+++ b/keyboards/drop/cstm80/readme.md
@@ -0,0 +1,24 @@
+# CSTM80
+
+The CSTM80 is a tenkeyless keyboard with customizable switch plates and weights, as well as a magnetically attached top case.
+
+* Keyboard Maintainer: [zvecr](https://github.com/zvecr)
+* Hardware Availability: [Drop CSTM80 Mechanical Keyboard](https://drop.com/buy/drop-cstm80-mechanical-keyboard)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make drop/cstm80:default
+
+Flashing example for this keyboard:
+
+    make drop/cstm80:default:flash
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 3 ways:
+
+* **Bootmagic reset**: Hold down the key at (0,0) in the matrix (usually the top left key or Escape) and plug in the keyboard
+* **Physical reset button**: Quickly double tap the button located under the spacebar
+* **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available
diff --git a/keyboards/drop/cstm80/rules.mk b/keyboards/drop/cstm80/rules.mk
new file mode 100644
index 000000000000..21d76468cf59
--- /dev/null
+++ b/keyboards/drop/cstm80/rules.mk
@@ -0,0 +1,4 @@
+UF2_DEVICE_TYPE_ID = 0x8bfa7750
+UF2CONV_ARGS = --device-type $(UF2_DEVICE_TYPE_ID)
+
+SRC += lib/common.c
diff --git a/keyboards/drop/lib/common.c b/keyboards/drop/lib/common.c
index b393e7650b4d..04845ed17a00 100644
--- a/keyboards/drop/lib/common.c
+++ b/keyboards/drop/lib/common.c
@@ -5,17 +5,15 @@
 #    include "quantum.h"
 #    include "rgb_matrix.h"
 
-#    define LED_FLAG_ANY_SWITCH (LED_FLAG_KEYLIGHT | LED_FLAG_MODIFIER | LED_FLAG_INDICATOR)
-
 #    ifdef RGB_MATRIX_CAPS_LOCK_INDEX
 bool rgb_matrix_indicators_kb(void) {
     if (!rgb_matrix_indicators_user()) {
         return false;
     }
 
-    if (host_keyboard_led_state().caps_lock) {
+    if (host_keyboard_led_state().caps_lock && (rgb_matrix_get_flags() != LED_FLAG_NONE)) {
         rgb_matrix_set_color(RGB_MATRIX_CAPS_LOCK_INDEX, RGB_WHITE);
-    } else if ((rgb_matrix_get_flags() & LED_FLAG_ANY_SWITCH) == 0) {
+    } else if (rgb_matrix_get_flags() == LED_FLAG_UNDERGLOW) {
         rgb_matrix_set_color(RGB_MATRIX_CAPS_LOCK_INDEX, RGB_OFF);
     }
     return true;
@@ -33,9 +31,9 @@ bool process_record_kb(uint16_t keycode, keyrecord_t *record) {
             case RGB_TOG:
                 switch (rgb_matrix_get_flags()) {
                     case LED_FLAG_ALL:
-                        rgb_matrix_set_flags(LED_FLAG_ANY_SWITCH);
+                        rgb_matrix_set_flags(LED_FLAG_KEYLIGHT | LED_FLAG_MODIFIER | LED_FLAG_INDICATOR);
                         break;
-                    case LED_FLAG_ANY_SWITCH:
+                    case (LED_FLAG_KEYLIGHT | LED_FLAG_MODIFIER | LED_FLAG_INDICATOR):
                         rgb_matrix_set_flags(LED_FLAG_UNDERGLOW);
                         break;
                     case LED_FLAG_UNDERGLOW: