diff --git a/apps/gpsrec/interface.html b/apps/gpsrec/interface.html
index 4c7270f0a..9f2211332 100644
--- a/apps/gpsrec/interface.html
+++ b/apps/gpsrec/interface.html
@@ -23,17 +23,7 @@ function saveKML(track,title) {
     </Placemark>
   </Document>
 </kml>`;
-  var a = document.createElement("a"),
-      file = new Blob([kml], {type: "application/vnd.google-earth.kml+xml"});
-  var url = URL.createObjectURL(file);
-  a.href = url;
-  a.download = title+".kml";
-  document.body.appendChild(a);
-  a.click();
-  setTimeout(function() {
-      document.body.removeChild(a);
-      window.URL.revokeObjectURL(url);
-  }, 0);
+  Util.saveFile(title+".kml", "application/vnd.google-earth.kml+xml", kml);
 }
 
 function saveGPX(track, title) {
@@ -56,17 +46,7 @@ function saveGPX(track, title) {
     </trkseg>
   </trk>
 </gpx>`;
-  var a = document.createElement("a"),
-      file = new Blob([gpx], {type: "application/gpx+xml"});
-  var url = URL.createObjectURL(file);
-  a.href = url;
-  a.download = title+".gpx";
-  document.body.appendChild(a);
-  a.click();
-  setTimeout(function() {
-      document.body.removeChild(a);
-      window.URL.revokeObjectURL(url);
-  }, 0);
+  Util.saveFile(title+".gpx", "application/gpx+xml", gpx);
 }
 
 function trackLineToObject(l, hasTrackNumber) {
diff --git a/apps/hrmaccevents/README.md b/apps/hrmaccevents/README.md
index ecd619152..57cf944c7 100644
--- a/apps/hrmaccevents/README.md
+++ b/apps/hrmaccevents/README.md
@@ -28,6 +28,10 @@ The CSV data contains the following columns:
 * PPG_o - `e.vcPPGoffs` from the `Bangle.on("HRM-raw"` event. This is the PPG offset used to map `e.vcPPG` to `e.raw` so there are no glitches when the exposure values in the sensor change.
 * BTHRM - BPM figure from external Bluetooth HRM device (this is our reference BPM)
 
+## FIXME
+
+The `custom.html` for the app uses the Puck.js lib directly when it should just use `customize.js` - it won't work well under Gadgetbridge and may fail on other platforms too
+
 ## Creator
 
 [halemmerich](https://github.com/halemmerich)
diff --git a/apps/hrmaccevents/custom.html b/apps/hrmaccevents/custom.html
index a5bf9796f..97cc7e0ab 100644
--- a/apps/hrmaccevents/custom.html
+++ b/apps/hrmaccevents/custom.html
@@ -4,6 +4,7 @@
   <link rel="stylesheet" href="../../css/spectre.min.css">
  </head>
  <body>
+<script src="../../core/lib/customize.js"></script>
 <script src="https://www.puck-js.com/puck.js"></script>
 <p>
 <div class="form-group">
@@ -23,20 +24,6 @@
 <p id="result"></p>
 <script>
 
-function saveCSV(filename, csvData) {
-  let a = document.createElement("a"),
-    file = new Blob([csvData], {type: "Comma-separated value file"});
-  let url = URL.createObjectURL(file);
-  a.href = url;
-  a.download = filename+".csv";
-  document.body.appendChild(a);
-  a.click();
-  setTimeout(function() {
-    document.body.removeChild(a);
-    window.URL.revokeObjectURL(url);
-  }, 0);
-}
-  
 function createCode(){
   //modes: 1 BT, 2 File
   return "var method=" + (document.getElementById("chkLocal").checked ? 2 : 1) + ";\n" + String.raw`
@@ -48,7 +35,7 @@ function createCode(){
   var gotBTHRM = false;
   var gotHRM = false;
   var gotAcc = false;
-  
+
   var events = -1;
   var hrmRaw,hrmPulse,bthrmPulse
 
@@ -59,9 +46,9 @@ function createCode(){
   let bthrmSettings = (require("Storage").readJSON("bthrm.json",1) || {});
 
   Bangle.setHRMPower(1);
-  
+
   if (bthrmSettings.replace) Bangle.origSetHRMPower(1);
-  
+
   if (Bangle.setBTHRMPower){
     Bangle.setBTHRMPower(1);
   } else {
@@ -166,7 +153,7 @@ function createCode(){
       drawStatus(free>0.25*process.env.STORAGE, h++, Math.floor(free/1024) + "K");
     }
   }
-  
+
   var intervalId = -1;
 
   g.setFont12x20();
@@ -181,7 +168,7 @@ function createCode(){
   drawStatusText("Events", h++);
   if (method == 2) drawStatusText("Storage", h++);
   updateStatus();
-  
+
   intervalId = setInterval(()=>{
     updateStatus();
   }, 1000);
@@ -221,8 +208,8 @@ document.getElementById("chkLocal").addEventListener("click", function() {
 
 window.addEventListener("message", function(event) {
   let msg = event.data;
-   if (msg.type=="readstoragefilersp") {
-    saveCSV("log.csv", msg.data);
+  if (msg.type=="readstoragefilersp") {
+    Util.saveCSV("log", msg.data);
   }
 }, false);
 
@@ -240,7 +227,7 @@ document.getElementById("btnDownload").addEventListener("click", function() {
 });
 
 document.getElementById("btnSave").addEventListener("click", function() {
-  saveCSV("log.csv", localStorage.getItem("data"));
+  Util.saveCSV("log", localStorage.getItem("data"));
 });
 
 function reset(){
@@ -289,7 +276,7 @@ document.getElementById("btnConnect").addEventListener("click", function() {
       l.forEach(onLine);
     });
     connection.write("reset();\n", function() {
-      setTimeout(function() {    
+      setTimeout(function() {
         connection.write("\x03\x10if(1){"+createCode()+"}\n",
           function() { console.log("Ready..."); });
       }, 1500);
diff --git a/apps/medicalinfo/interface.html b/apps/medicalinfo/interface.html
index 9376be32f..24d16ed89 100644
--- a/apps/medicalinfo/interface.html
+++ b/apps/medicalinfo/interface.html
@@ -95,17 +95,7 @@
         Util.showModal("Downloading...");
         let medicalInfoJson = getEditableContent();
         if (isJsonString(medicalInfoJson)) {
-          var a = document.createElement("a"),
-            file = new Blob([medicalInfoJson], { type: "application/json" });
-          var url = URL.createObjectURL(file);
-          a.href = url;
-          a.download = medicalInfoFile;
-          document.body.appendChild(a);
-          a.click();
-          setTimeout(function () {
-            document.body.removeChild(a);
-            window.URL.revokeObjectURL(url);
-          }, 0);
+          Util.saveFile(medicalInfoFile, "application/json", medicalInfoJson);
         } else {
           document.getElementById("info").innerHTML = errorFormat();
         }
diff --git a/apps/presentation_timer/interface.html b/apps/presentation_timer/interface.html
index 137ea8475..df1ddbbc5 100644
--- a/apps/presentation_timer/interface.html
+++ b/apps/presentation_timer/interface.html
@@ -96,17 +96,7 @@
         Util.showModal("Downloading...");
         let csvTimes = getEditableContent();
         if (isCorrectCsvString(csvTimes)) {
-          var a = document.createElement("a"),
-            file = new Blob([csvTimes], { type: "text/csv" });
-          var url = URL.createObjectURL(file);
-          a.href = url;
-          a.download = filePresentationTimer;
-          document.body.appendChild(a);
-          a.click();
-          setTimeout(function () {
-            document.body.removeChild(a);
-            window.URL.revokeObjectURL(url);
-          }, 0);
+          Util.saveFile(filePresentationTimer, "text/csv", csvTimes);
         } else {
           document.getElementById("info").innerHTML = errorFormat();
         }
diff --git a/apps/recorder/interface.html b/apps/recorder/interface.html
index 24dba9b64..f2774c79f 100644
--- a/apps/recorder/interface.html
+++ b/apps/recorder/interface.html
@@ -75,17 +75,7 @@ ${track.map(pt=>`            <gx:value>${0|pt.Skin}</gx:value>\n`).join("")}
     </Folder>
   </Document>
 </kml>`;
-  var a = document.createElement("a"),
-      file = new Blob([kml], {type: "application/vnd.google-earth.kml+xml"});
-  var url = URL.createObjectURL(file);
-  a.href = url;
-  a.download = title+".kml";
-  document.body.appendChild(a);
-  a.click();
-  setTimeout(function() {
-      document.body.removeChild(a);
-      window.URL.revokeObjectURL(url);
-  }, 0);
+  Util.saveFile(title+".kml", "application/vnd.google-earth.kml+xml", kml);
   showToast("Download finished.", "success");
 }
 
@@ -122,17 +112,7 @@ function saveGPX(track, title) {
     </trkseg>
   </trk>
 </gpx>`;
-  var a = document.createElement("a"),
-      file = new Blob([gpx], {type: "application/gpx+xml"});
-  var url = URL.createObjectURL(file);
-  a.href = url;
-  a.download = title+".gpx";
-  document.body.appendChild(a);
-  a.click();
-  setTimeout(function() {
-      document.body.removeChild(a);
-      window.URL.revokeObjectURL(url);
-  }, 0);
+  Util.saveFile(title+".gpx", "application/gpx+xml", gpx);
   showToast("Download finished.", "success");
 }
 
diff --git a/apps/swatch/interface.html b/apps/swatch/interface.html
index 1b239da3b..07b610735 100644
--- a/apps/swatch/interface.html
+++ b/apps/swatch/interface.html
@@ -75,7 +75,7 @@ function getLapTimes() {
           });
         }
         if (task=="download") {
-          Util.saveCSV(lap.n.slice(0,-5)+".csv", lap.d.map((d,n)=>[n+1,d].join(",")).join("\n"));
+          Util.saveCSV(lap.n.slice(0,-5), lap.d.map((d,n)=>[n+1,d].join(",")).join("\n"));
         }
       });
     }
diff --git a/apps/tempmonitor/interface.html b/apps/tempmonitor/interface.html
index 02d1fed91..eb7f7ab87 100644
--- a/apps/tempmonitor/interface.html
+++ b/apps/tempmonitor/interface.html
@@ -32,7 +32,7 @@ function getData() {
       <th>Month</th>
       <th>Day</th>
       <th>Time HH:mm</th>
-      <th>temperature</th>      
+      <th>temperature</th>
     </tr>`+data.trim().split("\n").map(l=>{
       l = l.split(";");
       return `<tr>
@@ -47,7 +47,7 @@ function getData() {
 
 // You can call a utility function to save the data
 document.getElementById("btnSave").addEventListener("click", function() {
-  Util.saveCSV("temphistory.csv", csvData);
+  Util.saveCSV("temphistory", csvData);
 });
 // Or you can also delete the file
 document.getElementById("btnDelete").addEventListener("click", function() {
diff --git a/apps/todolist/interface.html b/apps/todolist/interface.html
index 5b9cb038e..76033f172 100644
--- a/apps/todolist/interface.html
+++ b/apps/todolist/interface.html
@@ -95,17 +95,7 @@
         Util.showModal("Downloading...");
         let jsonTodos = getEditableContent();
         if (isJsonString(jsonTodos)) {
-          var a = document.createElement("a"),
-            file = new Blob([jsonTodos], { type: "application/json" });
-          var url = URL.createObjectURL(file);
-          a.href = url;
-          a.download = fileTodoList;
-          document.body.appendChild(a);
-          a.click();
-          setTimeout(function () {
-            document.body.removeChild(a);
-            window.URL.revokeObjectURL(url);
-          }, 0);
+          Util.saveFile(fileTodoList, "application/json", jsonTodos);
         } else {
           document.getElementById("info").innerHTML = errorFormat();
         }
diff --git a/core b/core
index 37a22e0c4..71813fe2e 160000
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit 37a22e0c49666ec3947ad0daaf5f5675101ca485
+Subproject commit 71813fe2eaf19987cec07db850ab9d1959694f96
