diff --git a/extensions/MasterMath/midi.js b/extensions/MasterMath/midi.js
new file mode 100644
index 0000000000..a0903cd37c
--- /dev/null
+++ b/extensions/MasterMath/midi.js
@@ -0,0 +1,269 @@
+// Name: MIDI
+// ID: masterMathMidi
+// Description: An extension that retrieves input from MIDI devices.
+// By: -MasterMath- <https://scratch.mit.edu/users/-MasterMath-/>
+// License: MPL-2.0
+
+(function (Scratch) {
+  "use strict";
+
+  if (!Scratch.extensions.unsandboxed) {
+    throw new Error("This MIDI extension must run unsandboxed!");
+  }
+
+  let midiInputDevices = [];
+  let midiDeviceInfo = [];
+  let notesOn = [];
+  let noteVelocities = [];
+  let lastNotePressed = 0;
+  let lastNoteReleased = 0;
+
+  if (navigator.requestMIDIAccess) {
+    navigator.requestMIDIAccess().then(onSuccess, onError);
+
+    function onSuccess(midiAccess) {
+      midiAccess.onstatechange = (event) => {
+        if (event.port.state == "connected") {
+          midiInputDevices.push(
+            `[id: "${event.port.id}" name: "${event.port.name}"]`
+          );
+          midiDeviceInfo.push([event.port.id, event.port.name]);
+        } else if (event.port.state == "disconnected") {
+          // Find and remove from midiInputDevices
+          const inputIndex = midiInputDevices.findIndex(
+            (item) =>
+              item === `[id: "${event.port.id}" name: "${event.port.name}"]`
+          );
+          if (inputIndex !== -1) midiInputDevices.splice(inputIndex, 1);
+
+          // Find and remove from midiDeviceInfo
+          const infoIndex = midiDeviceInfo.findIndex(
+            (item) => item[0] === event.port.id
+          );
+          if (infoIndex !== -1) midiDeviceInfo.splice(infoIndex, 1);
+        }
+      };
+
+      function onMIDIMessage(event) {
+        const [status, note, velocity] = event.data;
+        const command = status & 0xf0;
+        if (command === 0x90 && velocity > 0) {
+          notesOn.push(note);
+          noteVelocities.push([note, velocity]);
+          lastNotePressed = note;
+          Scratch.vm.runtime.startHats("midi_whenAnyNote", {
+            pressedReleased: "pressed",
+          });
+          Scratch.vm.runtime.startHats("midi_whenNote", {
+            note: note,
+            pressedReleased: "pressed",
+          });
+        } else if (command === 0x80 || (command === 0x90 && velocity === 0)) {
+          lastNoteReleased = note;
+          notesOn.splice(notesOn.indexOf(note), 1);
+          noteVelocities.splice(
+            noteVelocities.findIndex((subArray) => subArray[0] === note),
+            1
+          );
+          Scratch.vm.runtime.startHats("midi_whenAnyNote", {
+            pressedReleased: "released",
+          });
+          Scratch.vm.runtime.startHats("midi_whenNote", {
+            note: note,
+            pressedReleased: "released",
+          });
+        } else {
+          console.log(
+            `Other MIDI Message: Status=${status}, Note=${note}, Velocity=${velocity}, Timestamp ${event.timeStamp}`
+          );
+        }
+      }
+
+      midiAccess.inputs.forEach((entry) => {
+        entry.onmidimessage = onMIDIMessage;
+      });
+    }
+
+    function onError(err) {
+      throw new Error("MIDI Access Error:", err);
+    }
+  } else {
+    throw new Error("MIDI is not supported on this browser.");
+  }
+
+  class MIDI {
+    getInfo() {
+      return {
+        id: "masterMathMidi",
+        name: Scratch.translate("MIDI"),
+        blocks: [
+          {
+            opcode: "MIDIinputDevices",
+            blockType: Scratch.BlockType.REPORTER,
+            text: Scratch.translate("connected MIDI input devices"),
+            disableMonitor: true,
+          },
+          {
+            opcode: "midiDeviceInfo",
+            blockType: Scratch.BlockType.REPORTER,
+            text: Scratch.translate("[info] of MIDI device [number]"),
+            arguments: {
+              info: {
+                type: Scratch.ArgumentType.STRING,
+                menu: "infoMenu",
+              },
+              number: {
+                type: Scratch.ArgumentType.NUMBER,
+                defaultValue: 0,
+              },
+            },
+          },
+          "---",
+          {
+            opcode: "whenAnyNote",
+            blockType: Scratch.BlockType.EVENT,
+            text: Scratch.translate("when any note [pressedReleased]"),
+            isEdgeActivated: false,
+            shouldRestartExistingThreads: true,
+            arguments: {
+              pressedReleased: {
+                type: Scratch.ArgumentType.STRING,
+                menu: "pressedReleased",
+              },
+            },
+          },
+          {
+            opcode: "whenNote",
+            blockType: Scratch.BlockType.EVENT,
+            text: Scratch.translate("when note [note] [pressedReleased]"),
+            isEdgeActivated: false,
+            shouldRestartExistingThreads: true,
+            arguments: {
+              note: {
+                type: Scratch.ArgumentType.NOTE,
+                defaultValue: 60,
+              },
+              pressedReleased: {
+                type: Scratch.ArgumentType.STRING,
+                menu: "pressedReleased",
+              },
+            },
+          },
+          {
+            opcode: "noteOn",
+            blockType: Scratch.BlockType.BOOLEAN,
+            text: Scratch.translate("is note [note] on?"),
+            arguments: {
+              note: {
+                type: Scratch.ArgumentType.NOTE,
+                defaultValue: 60,
+              },
+            },
+          },
+          {
+            opcode: "noteVelocity",
+            blockType: Scratch.BlockType.REPORTER,
+            text: Scratch.translate("velocity of note [note]"),
+            arguments: {
+              note: {
+                type: Scratch.ArgumentType.NOTE,
+                defaultValue: 60,
+              },
+            },
+          },
+          {
+            opcode: "activeNotes",
+            blockType: Scratch.BlockType.REPORTER,
+            text: Scratch.translate("all active notes"),
+            disableMonitor: true,
+          },
+          {
+            opcode: "lastNote",
+            blockType: Scratch.BlockType.REPORTER,
+            text: Scratch.translate("last note [pressedReleased]"),
+            disableMonitor: true,
+            arguments: {
+              pressedReleased: {
+                type: Scratch.ArgumentType.STRING,
+                menu: "pressedReleased",
+              },
+            },
+          },
+        ],
+        menus: {
+          infoMenu: {
+            acceptReporters: false,
+            items: [
+              {
+                text: Scratch.translate("name"),
+                value: "name",
+              },
+              {
+                text: Scratch.translate("id"),
+                value: "id",
+              },
+            ],
+          },
+          pressedReleased: {
+            acceptReporters: false,
+            items: [
+              {
+                text: Scratch.translate("pressed"),
+                value: "pressed",
+              },
+              {
+                text: Scratch.translate("released"),
+                value: "released",
+              },
+            ],
+          },
+        },
+      };
+    }
+
+    MIDIinputDevices() {
+      return midiInputDevices;
+    }
+
+    midiDeviceInfo(args) {
+      args.number = Scratch.Cast.toNumber(args.number);
+      if (midiInputDevices[args.number] != null) {
+        return midiDeviceInfo[args.number][args.info == "id" ? 0 : 1];
+      } else {
+        return;
+      }
+    }
+
+    noteOn(args) {
+      return notesOn.includes(Scratch.Cast.toNumber(args.note));
+    }
+
+    noteVelocity(args) {
+      args.note = Scratch.Cast.toNumber(args.note);
+      if (
+        notesOn.includes(args.note) &&
+        noteVelocities.find((subArray) => subArray[0] === args.note)[1] !==
+          undefined
+      ) {
+        return noteVelocities.find((subArray) => subArray[0] === args.note)[1];
+      }
+    }
+
+    activeNotes() {
+      return notesOn;
+    }
+
+    lastNote({ pressedReleased }) {
+      switch (pressedReleased) {
+        case "pressed":
+          return lastNotePressed;
+        case "released":
+          return lastNoteReleased;
+        default:
+          return "";
+      }
+    }
+  }
+
+  Scratch.extensions.register(new MIDI());
+})(Scratch);
diff --git a/extensions/extensions.json b/extensions/extensions.json
index d8ed71e33d..86572b45e7 100644
--- a/extensions/extensions.json
+++ b/extensions/extensions.json
@@ -37,6 +37,7 @@
   "veggiecan/browserfullscreen",
   "shreder95ua/resolution",
   "XmerOriginals/closecontrol",
+  "MasterMath/midi",
   "navigator",
   "battery",
   "PwLDev/vibration",
diff --git a/images/MasterMath/midi.png b/images/MasterMath/midi.png
new file mode 100644
index 0000000000..f2f610e632
Binary files /dev/null and b/images/MasterMath/midi.png differ