diff --git a/Ooui.Forms/DisplayAlert.cs b/Ooui.Forms/DisplayAlert.cs
index fae811a..0770cfa 100644
--- a/Ooui.Forms/DisplayAlert.cs
+++ b/Ooui.Forms/DisplayAlert.cs
@@ -1,4 +1,4 @@
-using System.Web;
+using System;
 using Xamarin.Forms.Internals;
 
 namespace Ooui.Forms
@@ -31,7 +31,7 @@ namespace Ooui.Forms
                 ClassName = "close"
             };
 
-            _closeButton.AppendChild(new Span(HttpUtility.HtmlDecode("×")));
+            _closeButton.AppendChild(new Span("×"));
 
             var h4 = new Heading(4)
             {
diff --git a/Ooui.Forms/Forms.cs b/Ooui.Forms/Forms.cs
index c648cfa..e8e22e9 100644
--- a/Ooui.Forms/Forms.cs
+++ b/Ooui.Forms/Forms.cs
@@ -21,7 +21,7 @@ namespace Xamarin.Forms
                 return;
             IsInitialized = true;
 
-            Log.Listeners.Add (new DelegateLogListener ((c, m) => Trace.WriteLine (m, c)));
+            Log.Listeners.Add (new DelegateLogListener ((c, m) => System.Diagnostics.Debug.WriteLine (m, c)));
 
             Device.SetIdiom (TargetIdiom.Desktop);
             Device.PlatformServices = new OouiPlatformServices ();
@@ -64,7 +64,11 @@ namespace Xamarin.Forms
 
             public Assembly[] GetAssemblies ()
             {
+#if PCL
+                return new[] { typeof (Xamarin.Forms.View).GetTypeInfo ().Assembly, typeof (Forms.OouiPlatformServices).GetTypeInfo ().Assembly };
+#else
                 return AppDomain.CurrentDomain.GetAssemblies ();
+#endif
             }
 
             public string GetMD5Hash (string input)
@@ -140,6 +144,31 @@ namespace Xamarin.Forms
                 }
             }
 
+#if PCL
+
+            public delegate void TimerCallback(object state);
+
+            public sealed class Timer : CancellationTokenSource, IDisposable
+            {
+                public Timer (TimerCallback callback, object state, int dueTime, int period)
+                {
+                    Task.Run (async () => {
+                        await Task.Delay (dueTime).ConfigureAwait (false);
+                        if (!IsCancellationRequested)
+                            callback (state);
+                        while (!IsCancellationRequested) {
+                            await Task.Delay (period).ConfigureAwait (false);
+                            if (!IsCancellationRequested)
+                                callback (state);
+                        }
+                    });
+                }
+
+                public new void Dispose() { base.Cancel(); }
+            }
+
+#endif
+
             public void QuitApplication()
             {
             }
diff --git a/Ooui.Forms/Ooui.Forms.csproj b/Ooui.Forms/Ooui.Forms.csproj
index 440e8f2..b439ba6 100644
--- a/Ooui.Forms/Ooui.Forms.csproj
+++ b/Ooui.Forms/Ooui.Forms.csproj
@@ -9,16 +9,14 @@
     https://github.com/praeclarum/Ooui
     https://github.com/praeclarum/Ooui/blob/master/LICENSE
     https://github.com/praeclarum/Ooui.git
-    netstandard2.0
+    netstandard2.0;netstandard1.0
+    true
   
 
-  
-    true
-  
-  
-    
-    true
+  
+    PCL
   
+
   
     
   
diff --git a/Ooui.Forms/PageExtensions.cs b/Ooui.Forms/PageExtensions.cs
index 4ffe01d..b2174cb 100644
--- a/Ooui.Forms/PageExtensions.cs
+++ b/Ooui.Forms/PageExtensions.cs
@@ -5,6 +5,7 @@ namespace Xamarin.Forms
 {
     public static class PageExtensions
     {
+#if !PCL
         public static void Publish (this Xamarin.Forms.Page page, string path)
         {
             Ooui.UI.Publish (path, () => page.CreateElement ());
@@ -15,6 +16,7 @@ namespace Xamarin.Forms
             var lazyPage = new Lazy ((() => page.CreateElement ()), true);
             Ooui.UI.Publish (path, () => lazyPage.Value);
         }
+#endif
 
         public static Ooui.Element GetOouiElement (this Xamarin.Forms.Page page)
         {
diff --git a/Ooui.Forms/Platform.cs b/Ooui.Forms/Platform.cs
index 96197cb..635fe97 100644
--- a/Ooui.Forms/Platform.cs
+++ b/Ooui.Forms/Platform.cs
@@ -4,7 +4,6 @@ using System.Threading.Tasks;
 using Ooui.Forms.Renderers;
 using Xamarin.Forms;
 using Xamarin.Forms.Internals;
-using System.Web;
 
 namespace Ooui.Forms
 {
@@ -142,7 +141,7 @@ namespace Ooui.Forms
         void AddChild (VisualElement view)
         {
             if (!Application.IsApplicationOrNull (view.RealParent))
-                Console.Error.WriteLine ("Tried to add parented view to canvas directly");
+                System.Diagnostics.Debug.WriteLine ("Tried to add parented view to canvas directly");
 
             if (GetRenderer (view) == null) {
                 var viewRenderer = CreateRenderer (view);
@@ -152,7 +151,7 @@ namespace Ooui.Forms
                 viewRenderer.SetElementSize (new Size (640, 480));
             }
             else
-                Console.Error.WriteLine ("Potential view double add");
+                System.Diagnostics.Debug.WriteLine ("Potential view double add");
         }
 
         void HandleRendererStyle_PropertyChanged (object sender, System.ComponentModel.PropertyChangedEventArgs e)
diff --git a/Ooui.Forms/Renderers/ImageRenderer.cs b/Ooui.Forms/Renderers/ImageRenderer.cs
index 3f9e6e2..7b429bc 100644
--- a/Ooui.Forms/Renderers/ImageRenderer.cs
+++ b/Ooui.Forms/Renderers/ImageRenderer.cs
@@ -139,8 +139,12 @@ namespace Ooui.Forms.Renderers
 
     public sealed class FileImageSourceHandler : IImageSourceHandler
     {
+#pragma warning disable 1998
         public async Task LoadImageAsync (ImageSource imagesource, CancellationToken cancelationToken = default (CancellationToken), float scale = 1f)
         {
+#if PCL
+            return null;
+#else
             string image = null;
             var filesource = imagesource as FileImageSource;
             var file = filesource?.File;
@@ -155,6 +159,7 @@ namespace Ooui.Forms.Renderers
                 }
             }
             return image;
+#endif
         }
     }
 
@@ -162,6 +167,9 @@ namespace Ooui.Forms.Renderers
     {
         public async Task LoadImageAsync (ImageSource imagesource, CancellationToken cancelationToken = default (CancellationToken), float scale = 1f)
         {
+#if PCL
+            return null;
+#else
             string image = null;
             var streamsource = imagesource as StreamImageSource;
             if (streamsource?.Stream != null) {
@@ -171,7 +179,7 @@ namespace Ooui.Forms.Renderers
                         using (var outputStream = new System.IO.MemoryStream (data)) {
                             await streamImage.CopyToAsync (outputStream, 4096, cancelationToken).ConfigureAwait (false);
                         }
-                        var hash = Ooui.UI.Hash (data);
+                        var hash = Ooui.Utilities.Hash (data);
                         var etag = "\"" + hash + "\"";
                         image = "/images/" + hash;
                         if (Ooui.UI.TryGetFileContentAtPath (image, out var file) && file.Etag == etag) {
@@ -188,6 +196,7 @@ namespace Ooui.Forms.Renderers
                 System.Diagnostics.Debug.WriteLine ("Could not load image: {0}", streamsource);
             }
             return image;
+#endif
         }
     }
 
diff --git a/Ooui.Forms/ResourcesProvider.cs b/Ooui.Forms/ResourcesProvider.cs
index c0c05a3..c71be52 100644
--- a/Ooui.Forms/ResourcesProvider.cs
+++ b/Ooui.Forms/ResourcesProvider.cs
@@ -40,3 +40,12 @@ namespace Ooui.Forms
 		}
 	}
 }
+
+#if PCL
+namespace System.Collections.Concurrent
+{
+	class ConcurrentDictionary : Dictionary
+	{		
+	}
+}
+#endif
diff --git a/Ooui.Wasm/ooui-sample.html b/Ooui.Wasm/ooui-sample.html
index cfb1dfb..f47470c 100644
--- a/Ooui.Wasm/ooui-sample.html
+++ b/Ooui.Wasm/ooui-sample.html
@@ -44,6 +44,9 @@
 			"System.Xml.dll",
 			"System.Xml.ReaderWriter.dll",
 			"System.Xml.XDocument.dll",
+			"Xamarin.Forms.Core.dll",
+			"Xamarin.Forms.Platform.dll",
+			"Xamarin.Forms.Xaml.dll",
 			"Ooui.dll",
 			mainAsmName + ".dll"
 		];
diff --git a/Ooui/UI.cs b/Ooui/UI.cs
index 893ef63..dc87fa9 100644
--- a/Ooui/UI.cs
+++ b/Ooui/UI.cs
@@ -14,10 +14,8 @@ namespace Ooui
         public const int MaxFps = 30;
 
 #if !PCL
-        static readonly ManualResetEvent started = new ManualResetEvent (false);
 
-        [ThreadStatic]
-        static System.Security.Cryptography.SHA256 sha256;
+        static readonly ManualResetEvent started = new ManualResetEvent (false);
 
         static CancellationTokenSource serverCts;
 
@@ -82,22 +80,7 @@ namespace Ooui
                     clientJsBytes = Encoding.UTF8.GetBytes (r.ReadToEnd ());
                 }
             }
-            clientJsEtag = "\"" + Hash (clientJsBytes) + "\"";
-        }
-
-        public static string Hash (byte[] bytes)
-        {
-            var sha = sha256;
-            if (sha == null) {
-                sha = System.Security.Cryptography.SHA256.Create ();
-                sha256 = sha;
-            }
-            var data = sha.ComputeHash (bytes);
-            StringBuilder sBuilder = new StringBuilder ();
-            for (int i = 0; i < data.Length; i++) {
-                sBuilder.Append (data[i].ToString ("x2"));
-            }
-            return sBuilder.ToString ();
+            clientJsEtag = "\"" + Utilities.Hash (clientJsBytes) + "\"";
         }
 
         static void Publish (string path, RequestHandler handler)
@@ -129,13 +112,13 @@ namespace Ooui
             if (contentType == null) {
                 contentType = GuessContentType (path, filePath);
             }
-            var etag = "\"" + Hash (data) + "\"";
+            var etag = "\"" + Utilities.Hash (data) + "\"";
             Publish (path, new DataHandler (data, etag, contentType));
         }
 
         public static void PublishFile (string path, byte[] data, string contentType)
         {
-            var etag = "\"" + Hash (data) + "\"";
+            var etag = "\"" + Utilities.Hash (data) + "\"";
             Publish (path, new DataHandler (data, etag, contentType));
         }
 
@@ -180,7 +163,7 @@ namespace Ooui
         public static void PublishJson (string path, object value)
         {
             var data = JsonHandler.GetData (value);
-            var etag = "\"" + Hash (data) + "\"";
+            var etag = "\"" + Utilities.Hash (data) + "\"";
             Publish (path, new DataHandler (data, etag, JsonHandler.ContentType));
         }
 
@@ -379,13 +362,18 @@ namespace Ooui
             }
         }
 
+        static string EscapeHtml (string text)
+        {
+            return text.Replace ("&", "&").Replace ("<", "<");
+        }
+
         public static void RenderTemplate (TextWriter writer, string webSocketPath, string title, string initialHtml)
         {
             writer.Write (@"
 
 
   ");
-            writer.Write (title.Replace ("&", "&").Replace ("<", "<"));
+            writer.Write (EscapeHtml (title));
             writer.Write (@"
   
   ");
diff --git a/Ooui/Utilities.cs b/Ooui/Utilities.cs
new file mode 100644
index 0000000..a850099
--- /dev/null
+++ b/Ooui/Utilities.cs
@@ -0,0 +1,69 @@
+using System;
+using System.Text;
+
+namespace Ooui
+{
+    public static class Utilities
+    {
+#if PCL
+
+        static readonly uint[] crcTable;
+
+        static Utilities ()
+        {
+            uint p = 0x04C11DB7;
+            crcTable = new uint[256];
+            for (uint c = 0; c <= 0xFF; c++) {
+                crcTable[c] = CrcReflect (c, 8) << 24;
+                for (uint i = 0; i < 8; i++) {
+                    crcTable[c] = (crcTable[c] << 1) ^ (((crcTable[c] & (1u << 31)) != 0) ? p : 0);
+                }
+                crcTable[c] = CrcReflect (crcTable[c], 32);
+            }
+        }
+
+        static uint CrcReflect (uint r, byte c)
+        {
+            uint v = 0;
+            for (int i = 1; i < (c + 1); i++) {
+                if ((r & 1) != 0) {
+                    v |= (1u << (c - i));
+                }
+                r >>= 1;
+            }
+            return v;
+        }
+
+        public static string Hash (byte[] bytes)
+        {
+            uint crc = 0xffffffffu;
+            for (var i = 0; i < bytes.Length; i++) {
+                crc = (crc >> 8) ^ crcTable[(crc & 0xff) ^ bytes[i]];
+            }
+            crc ^= 0xffffffffu;
+            return crc.ToString ("x8");
+        }
+
+#else
+
+        [ThreadStatic]
+        static System.Security.Cryptography.SHA256 sha256;
+
+        public static string Hash (byte[] bytes)
+        {
+            var sha = sha256;
+            if (sha == null) {
+                sha = System.Security.Cryptography.SHA256.Create ();
+                sha256 = sha;
+            }
+            var data = sha.ComputeHash (bytes);
+            StringBuilder sBuilder = new StringBuilder ();
+            for (int i = 0; i < data.Length; i++) {
+                sBuilder.Append (data[i].ToString ("x2"));
+            }
+            return sBuilder.ToString ();
+        }
+
+#endif
+    }
+}