diff --git a/packages/serial/README.md b/packages/serial/README.md
new file mode 100644
index 00000000..5adb2282
--- /dev/null
+++ b/packages/serial/README.md
@@ -0,0 +1,4 @@
+# @strudel.cycles/serial
+
+This package adds webserial functionality to strudel Patterns, for e.g. sending messages to arduino microcontrollers.
+
diff --git a/packages/serial/package.json b/packages/serial/package.json
new file mode 100644
index 00000000..5517c831
--- /dev/null
+++ b/packages/serial/package.json
@@ -0,0 +1,24 @@
+{
+  "name": "@strudel.cycles/serial",
+  "version": "0.0.6",
+  "description": "Webserial API for strudel",
+  "main": "serial.mjs",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/tidalcycles/strudel.git"
+  },
+  "keywords": [
+    "titdalcycles",
+    "strudel",
+    "pattern",
+    "livecoding",
+    "algorave"
+  ],
+  "author": "Alex McLean <alex@slab.org>",
+  "license": "GPL-3.0-or-later",
+  "bugs": {
+    "url": "https://github.com/tidalcycles/strudel/issues"
+  },
+  "homepage": "https://github.com/tidalcycles/strudel#readme",
+  "dependencies": {}
+}
diff --git a/packages/serial/serial.mjs b/packages/serial/serial.mjs
new file mode 100644
index 00000000..00e78f58
--- /dev/null
+++ b/packages/serial/serial.mjs
@@ -0,0 +1,55 @@
+import { Pattern, isPattern } from '@strudel.cycles/core';
+
+var serialWriter;
+var choosing = false;
+
+export async function getWriter() {
+  if (choosing) {
+    return;
+  }
+  choosing = true;
+  if (serialWriter) {
+    return serialWriter;
+  }
+  if ('serial' in navigator) {
+    const port = await navigator.serial.requestPort();
+    await port.open({ baudRate: 115200 });
+    const textEncoder = new TextEncoderStream();
+    const writableStreamClosed = textEncoder.readable.pipeTo(port.writable);
+    const writer = textEncoder.writable.getWriter();
+    serialWriter = function (message) {
+      writer.write(message)
+    }
+  }
+  else {
+    throw('Webserial is not available in this browser.')
+  }
+}
+
+const latency = 0.1;
+
+// Pattern.prototype.midi = function (output: string | number, channel = 1) {
+Pattern.prototype.serial = function () {
+  return this._withEvent((event) => {
+    getWriter();
+    if (!serialWriter) {
+      return event;
+    }
+    const onTrigger = (time, event, currentTime) => {
+      var message = "";
+      if (typeof event.value === 'object') {
+        for (const [key, val] of Object.entries(event.value).flat()) {
+          message += `${key}:${val};`
+        }
+      }
+      else {
+        message = event.value;
+      }
+      const offset = (time - currentTime + latency) * 1000;
+      //const ts = Math.floor(Date.now() + offset);
+      console.log(`sending ${message}`)
+      window.setTimeout(serialWriter, offset, message)
+    };
+    return event.setContext({ ...event.context, onTrigger });
+  });
+};
diff --git a/repl/src/App.js b/repl/src/App.js
index bfff776b..ef8e84d5 100644
--- a/repl/src/App.js
+++ b/repl/src/App.js
@@ -30,6 +30,7 @@ import '@strudel.cycles/core/speak.mjs';
 import '@strudel.cycles/tone/pianoroll.mjs';
 import '@strudel.cycles/tone/draw.mjs';
 import '@strudel.cycles/osc/osc.mjs';
+import '@strudel.cycles/serial/serial.mjs';
 import controls from '@strudel.cycles/core/controls.mjs';
 
 extend(