diff --git a/apps.json b/apps.json
index a4fc86f5b..a28e57c59 100644
--- a/apps.json
+++ b/apps.json
@@ -1,4 +1,15 @@
 [
+  { "id": "fwupdate",
+    "name": "Firmware Update",
+    "icon": "app.png",
+    "version":"0.01",
+    "description": "Uploads new Espruino firmwares to Bangle.js 2",
+    "custom": "custom.html", "customConnect":true,
+    "tags": "tools,system,b2",
+    "type": "RAM",
+    "storage": [ ],
+    "sortorder" : -20
+  },
   { "id": "boot",
     "name": "Bootloader",
     "tags": "tool,system,b2",
diff --git a/apps/fwupdate/ChangeLog b/apps/fwupdate/ChangeLog
new file mode 100644
index 000000000..ec66c5568
--- /dev/null
+++ b/apps/fwupdate/ChangeLog
@@ -0,0 +1 @@
+0.01: Initial version
diff --git a/apps/fwupdate/app.png b/apps/fwupdate/app.png
new file mode 100644
index 000000000..1fabf06a2
Binary files /dev/null and b/apps/fwupdate/app.png differ
diff --git a/apps/fwupdate/custom.html b/apps/fwupdate/custom.html
new file mode 100644
index 000000000..5286ef062
--- /dev/null
+++ b/apps/fwupdate/custom.html
@@ -0,0 +1,284 @@
+<html>
+  <head>
+    <link rel="stylesheet" href="../../css/spectre.min.css">
+  </head>
+  <body>
+    <div id="fw-unknown">
+    <p>Firmware updates using the App Loader are only possible on
+    Bangle.js 2. For firmware updates on Bangle.js 1 please
+    <a href="https://www.espruino.com/Bangle.js#firmware-updates" target="_blank">see the Bangle.js 1 instructions</a></p>
+  </div>
+    <div id="fw-ok" style="display:none">
+      <p>Please upload a hex file here. This file should be the <code>.app_hex</code>
+      file, *not* the normal <code>.hex</code> (as that contains the bootloader as well).</p>
+
+      <input class="form-input" type="file" id="fileLoader" accept=".hex,.app_hex"/><br>
+      <p><button id="upload" class="btn btn-primary">Upload</button></p>
+    </div>
+
+    <pre id="log"></pre>
+
+    <script src="../../core/lib/customize.js"></script>
+
+    <script>
+var hex;
+var hexJS; // JS to upload hex
+var HEADER_LEN = 16; // size of app flash header
+var MAX_ADDRESS = 0x1000000; // discount anything in hex file above this
+var VERSION = 0x12345678; // VERSION! Use this to test firmware in JS land
+var DEBUG = false;
+
+function log(t) {
+  document.getElementById('log').innerText += t+"\n";
+  console.log(t);
+}
+
+function onInit(device) {
+  console.log(device);
+  if (device && device.id=="BANGLEJS2") {
+    document.getElementById("fw-unknown").style = "display:none";
+    document.getElementById("fw-ok").style = "";
+  }
+}
+
+function checkForFileOnServer() {
+  /*function getURL(url, callback) {
+  	var xhr = new XMLHttpRequest();
+    xhr.onload = callback;
+    baseURL = url;
+    xhr.open("GET", baseURL);
+    xhr.responseType = "document";
+    xhr.send();
+  }
+
+  function getFilesFromURL(url, regex, callback) {
+  	getURL(url, function() {
+  		var files = [];
+  		var elements = this.responseXML.getElementsByTagName("a");
+  		for (var i=0;i<elements.length;i++) {
+  			var href = elements[i].href;
+  			if (regex.exec(href)) {
+  				files.push(href);
+  			}
+  		}
+  		callback(files);
+  	});
+  }
+
+  var regex = new RegExp("_bangle2");
+
+	var domFirmware = document.getElementById("latest-firmware");
+	getFilesFromURL("https://www.espruino.com/binaries/", regex, function(releaseFiles) {
+		releaseFiles.sort().reverse().forEach(function(f) {
+			var name = f.substr(f.substr(0,f.length-1).lastIndexOf('/')+1);
+			domFirmware.innerHTML += 'Release: <a href="'+f+'">'+name+'</a><br/>';
+		});
+		getFilesFromURL("https://www.espruino.com/binaries/travis/master/",regex, function(travisFiles) {
+			travisFiles.forEach(function(f) {
+				var name = f.substr(f.lastIndexOf('/')+1);
+				domFirmware.innerHTML += 'Cutting Edge build: <a href="'+f+'">'+name+'</a><br/>';
+			});
+      document.getElementById("checking-server").style = "display:none";
+      document.getElementById("main-ui").style = "";
+		});
+	});*/
+}
+
+function downloadFile() {
+  /*response = await fetch(APP_HEX_PATH+"readlink.php?link="+APP_HEX_FILE, {
+    method: 'GET',
+    cache: 'no-cache',
+  });
+  if (response.ok) {
+    blob = await response.blob();
+    data = await blob.text();
+    document.getElementById("latest-firmware").innerHTML="(<b>"+data.toString()+"</b>)";
+  }*/
+}
+
+function handleFileSelect(event) {
+  if (event.target.files.length!=1) {
+    log("More than one file selected!");
+    return;
+  }
+  var reader = new FileReader();
+  reader.onload = function(event) {
+    hex = event.target.result.split("\n");
+    document.getElementById("upload").style = ""; // show upload
+    fileLoaded();
+  };
+  reader.readAsText(event.target.files[0]);
+};
+
+
+function parseLines(dataCallback) {
+  var addrHi = 0;
+  hex.forEach(function(hexline) {
+    if (DEBUG) console.log(hexline);
+    var bytes = hexline.substr(1,2);
+    var addrLo = parseInt(hexline.substr(3,4),16);
+    var cmd = hexline.substr(7,2);
+    if (cmd=="02") addrHi = parseInt(hexline.substr(9,4),16) << 4; // Extended Segment Address
+    else if (cmd=="04") addrHi = parseInt(hexline.substr(9,4),16) << 16; // Extended Linear Address
+    else if (cmd=="00") {
+      var addr = addrHi + addrLo;
+      var data = [];
+      for (var i=0;i<16;i++) data.push(parseInt(hexline.substr(9+(i*2),2),16));
+      dataCallback(addr,data);
+    }
+  });
+}
+
+function CRC32(data) {
+  var crc = 0xFFFFFFFF;
+  data.forEach(function(d) {
+    crc^=d;
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+    crc=(crc>>>1)^(0xEDB88320&-(crc&1));
+  });
+  return (~crc)>>>0; // >>>0 converts to unsigned 32-bit integer
+}
+
+function btoa(input) {
+  var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+  var out = "";
+  var i=0;
+  while (i<input.length) {
+    var octet_a = 0|input[i++];
+    var octet_b = 0;
+    var octet_c = 0;
+    var padding = 0;
+    if (i<input.length) {
+      octet_b = 0|input[i++];
+      if (i<input.length) {
+        octet_c = 0|input[i++];
+        padding = 0;
+      } else
+        padding = 1;
+    } else
+      padding = 2;
+    var triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c;
+    out += b64[(triple >> 18) & 63] +
+           b64[(triple >> 12) & 63] +
+           ((padding>1)?'=':b64[(triple >> 6) & 63]) +
+           ((padding>0)?'=':b64[triple & 63]);
+  }
+  return out;
+}
+
+// To upload the app, we write to external flash
+function createJS_app(binary, bin32, startAddress, endAddress, HEADER_LEN) {
+  /* typedef struct {
+    uint32_t address;
+    uint32_t size;
+    uint32_t CRC;
+    uint32_t version;
+  } FlashHeader; */
+  bin32[0] = startAddress;
+  bin32[1] = endAddress - startAddress;
+  bin32[2] = CRC32(new Uint8Array(binary.buffer, HEADER_LEN));
+  bin32[3] = VERSION; // VERSION! Use this to test ourselves
+  console.log("CRC 0x"+bin32[2].toString(16));
+  hexJS = "";//`\x10if (E.CRC32(E.memoryArea(${startAddress},${endAddress-startAddress}))==${bin32[2]}) { print("FIRMWARE UP TO DATE!"); load();}\n`;
+  hexJS += '\x10var s = require("Storage");\n';
+  var CHUNKSIZE = 1024;
+  for (var i=0;i<binary.length;i+=CHUNKSIZE) {
+    var l = binary.length-i;
+    if (l>CHUNKSIZE) l=CHUNKSIZE;
+    var chunk = btoa(new Uint8Array(binary.buffer, i, l));
+    hexJS += `\x10s.write('.firmware', atob("${chunk}"), 0x${i.toString(16)}, ${binary.length});\n`;
+  }
+  hexJS += '\x10setTimeout(()=>E.showMessage("Rebooting..."),50);\n';
+  hexJS += '\x10setTimeout(()=>E.reboot(), 1000);\n';
+}
+
+
+// To upload the bootloader, we write to internal flash, right over bootloader
+function createJS_bootloader(binary, startAddress, endAddress) {
+  var crc = CRC32(binary);
+  console.log("CRC 0x"+crc.toString(16));
+  hexJS = `\x10if (E.CRC32(E.memoryArea(${startAddress},${endAddress-startAddress}))==${crc}) { print("BOOTLOADER UP TO DATE!"); load();}\n`;
+  hexJS += `\x10var _fw = new Uint8Array(${binary.length})\n`;
+  var CHUNKSIZE = 1024;
+  for (var i=0;i<binary.length;i+=CHUNKSIZE) {
+    var l = binary.length-i;
+    if (l>CHUNKSIZE) l=CHUNKSIZE;
+    var chunk = btoa(new Uint8Array(binary.buffer, binary.byteOffset+i, l));
+    hexJS += '\x10_fw.set(atob("'+chunk+'"), 0x'+(i).toString(16)+');\n';
+  }
+//   hexJS += `\x10(function() {
+//   if (E.CRC32(_fw)!=${crc}) throw "Invalid CRC!";
+//   var f = require("Flash");
+//   for (var i=${startAddress};i<${endAddress};i+=4096) f.erasePage(i);
+//   f.write(_fw,${startAddress});
+//   E.reboot();
+// })();\n`;
+  hexJS += `\x10if (E.CRC32(_fw)!=${crc}) throw "Invalid CRC: 0x"+E.CRC32(_fw).toString(16);\n`;
+  hexJS += '\x10var f = require("Flash");\n';
+  for (var i=startAddress;i<endAddress;i+=4096)
+    hexJS += '\x10f.erasePage(0x'+i.toString(16)+');\n';
+  hexJS += `\x10f.write(_fw,${startAddress});\n`;
+  // hexJS += '\x10setTimeout(()=>E.showMessage("Rebooting..."),50);\n';
+  // hexJS += '\x10setTimeout(()=>E.reboot(), 2000);\n';
+}
+
+function fileLoaded() {
+  // Work out addresses
+  var startAddress, endAddress = 0;
+  parseLines(function(addr, data) {
+    if (addr>MAX_ADDRESS) return; // ignore data out of range
+    if (startAddress === undefined || addr<startAddress)
+      startAddress = addr;
+    var end = addr + data.length;
+    if (end > endAddress)
+      endAddress = end;
+  });
+  console.log(`// Data from 0x${startAddress.toString(16)} to 0x${endAddress.toString(16)} (${endAddress-startAddress} bytes)`);
+  // Work out data
+  var HEADER_LEN = 16;
+  var binary = new Uint8Array(HEADER_LEN + endAddress-startAddress);
+  binary.fill(0); // actually seems to assume a block is filled with 0 if not complete
+  var bin32 = new Uint32Array(binary.buffer);
+  parseLines(function(addr, data) {
+    if (addr>MAX_ADDRESS) return; // ignore data out of range
+    var binAddr = HEADER_LEN + addr - startAddress;
+    binary.set(data, binAddr);
+    if (DEBUG) console.log("i",addr.toString(16).padStart(8,0), data.map(x=>x.toString(16).padStart(2,0)).join(" "));
+    //console.log("o",new Uint8Array(binary.buffer, binAddr, data.length));
+  });
+
+  if (startAddress == 0xf7000) {
+    console.log("Bootloader - Writing to internal flash");
+    createJS_bootloader(new Uint8Array(binary.buffer, HEADER_LEN), startAddress, endAddress);
+  } else {
+    console.log("App - Writing to external flash");
+    createJS_app(binary, bin32, startAddress, endAddress);
+  }
+
+}
+
+function handleUpload() {
+  if (!hexJS) {
+    log("Hex file not loaded!");
+    return;
+  }
+  sendCustomizedApp({
+    storage:[
+      {name:"RAM", content:hexJS},
+    ]
+  });
+}
+
+document.getElementById('fileLoader').addEventListener('change', handleFileSelect, false);
+document.getElementById("upload").addEventListener("click", handleUpload);
+checkForFileOnServer();
+
+    </script>
+  </body>
+</html>
