diff --git a/README.md b/README.md
index 9dd066f6..53326e7e 100644
--- a/README.md
+++ b/README.md
@@ -127,7 +127,7 @@ Binding code:
 
 It's very simple.
 
-ReactiveProperty doesn't provide base class by ViewModel, which means that ReactiveProperty can be used together with another MVVM library like Prism, MVVMLight, etc...
+ReactiveProperty doesn't provide base class by ViewModel, which means that ReactiveProperty can be used together with another MVVM libraries such as Prism, Microsoft.Toolkit.Mvvm and etc.
 
 ## Documentation
 
@@ -140,6 +140,7 @@ ReactiveProperty doesn't provide base class by ViewModel, which means that React
 |[ReactiveProperty](https://www.nuget.org/packages/ReactiveProperty/)|![](https://img.shields.io/nuget/v/ReactiveProperty.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.svg)|The package includes all core features, and the target platform is .NET Standard 2.0. It fits almost all situations.|
 |[ReactiveProperty.Core](https://www.nuget.org/packages/ReactiveProperty.Core/)|![](https://img.shields.io/nuget/v/ReactiveProperty.Core.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.Core.svg)|The package includes minimum classes such as `ReactivePropertySlim<T>` and `ReadOnlyReactivePropertySlim<T>`. And this doesn't have any dependency even System.Reactive. If you don't need Rx features, then it fits.|
 |[ReactiveProperty.WPF](https://www.nuget.org/packages/ReactiveProperty.WPF/)|![](https://img.shields.io/nuget/v/ReactiveProperty.WPF.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.WPF.svg)|The package includes EventToReactiveProperty and EventToReactiveCommand for WPF. This is for .NET Core 3.0 or later and .NET Framework 4.7.2 or later.|
+|[ReactiveProperty.Blazor](https://www.nuget.org/packages/ReactiveProperty.Blazor/)|![](https://img.shields.io/nuget/v/ReactiveProperty.Blazor.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.Blazor.svg)|The package includes validation support for EditForm component of Blazor with ReactiveProperty validation feature. This is for .NET 6.0 or later. |
 |[ReactiveProperty.UWP](https://www.nuget.org/packages/ReactiveProperty.UWP/)|![](https://img.shields.io/nuget/v/ReactiveProperty.UWP.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.UWP.svg)|The package includes EventToReactiveProperty and EventToReactiveCommand for UWP.|
 |[ReactiveProperty.XamarinAndroid](https://www.nuget.org/packages/ReactiveProperty.XamarinAndroid/)|![](https://img.shields.io/nuget/v/ReactiveProperty.XamarinAndroid.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.XamarinAndroid.svg)|The package includes many extension methods to create IObservable from events for Xamarin.Android native.|
 |[ReactiveProperty.XamariniOS](https://www.nuget.org/packages/ReactiveProperty.XamariniOS/)|![](https://img.shields.io/nuget/v/ReactiveProperty.XamariniOS.svg)![](https://img.shields.io/nuget/dt/ReactiveProperty.XamariniOS.svg)|The package includes many extension methods to bind ReactiveProperty and ReactiveCommand to Xamarin.iOS native controls.|
diff --git a/Samples/Blazor/BlazorSample.Shared/Pages/Index.razor b/Samples/Blazor/BlazorSample.Shared/Pages/Index.razor
index 79d42307..cc8bc717 100644
--- a/Samples/Blazor/BlazorSample.Shared/Pages/Index.razor
+++ b/Samples/Blazor/BlazorSample.Shared/Pages/Index.razor
@@ -1,27 +1,43 @@
-@using Reactive.Bindings.Components
+@using Reactive.Bindings
+@using Reactive.Bindings.Extensions
+@using Reactive.Bindings.Components
+@using System.Reactive.Linq
+@using System.Reactive.Disposables
+@using System.Reactive.Concurrency
 @page "/"
-@inject IndexViewModel _viewModel
+@implements IDisposable
+@inject ValidationViewModel _validationViewModel
+@inject HelloWorldViewModel _helloWorldViewModel
 
-<h3>ReactivePropertiesValidator sample</h3>
+<h1>ReactiveProperty samples</h1>
 
-<EditForm Model="_viewModel" OnInvalidSubmit="InvalidSubmit" OnValidSubmit="ValidSubmit">
+<h3>Hello world</h3>
+
+<input class="form-control" type="text" @bind="_helloWorldViewModel.Input.Value" @bind:event="oninput" />
+<div class="alert alert-primary">
+    @_helloWorldViewModel.Output.Value
+</div>
+
+<h3>Validation sample</h3>
+
+<EditForm Model="_validationViewModel" OnInvalidSubmit="InvalidSubmit" OnValidSubmit="ValidSubmit">
     <ReactivePropertiesValidator />
 
     <ValidationSummary />
 
     <div class="mb-3">
         <label for="firstName">First name</label>
-        <InputText @bind-Value="_viewModel.FirstName.Value" class="form-control" />
-        <ValidationMessage For="() => _viewModel.FirstName.Value" />
+        <InputText @bind-Value="_validationViewModel.FirstName.Value" class="form-control" />
+        <ValidationMessage For="() => _validationViewModel.FirstName.Value" />
     </div>
     <div class="mb-3">
         <label for="firstName">Last name</label>
-        <InputText @bind-Value="_viewModel.LastName.Value" class="form-control" />
-        <ValidationMessage For="() => _viewModel.LastName.Value" />
+        <InputText @bind-Value="_validationViewModel.LastName.Value" class="form-control" />
+        <ValidationMessage For="() => _validationViewModel.LastName.Value" />
     </div>
 
     <div class="mb-3">
-        <span>Full name: @_viewModel.FullName.Value</span>
+        <span>Full name: @_validationViewModel.FullName.Value</span>
     </div>
 
     <button type="submit" class="btn btn-primary">Submit</button>
@@ -35,6 +51,7 @@
 }
 
 @code {
+    private readonly CompositeDisposable _disposable = new();
     private string? _message;
 
     private void InvalidSubmit(EditContext context)
@@ -46,4 +63,16 @@
     {
         _message = "ValidSubmit was invoked.";
     }
+
+    protected override void OnInitialized()
+    {
+        _validationViewModel.AddTo(_disposable);
+        _helloWorldViewModel.AddTo(_disposable);
+
+        _helloWorldViewModel.Output
+            .Subscribe(_ => InvokeAsync(StateHasChanged))
+            .AddTo(_disposable);
+    }
+
+    public void Dispose() => _disposable.Dispose();
 }
diff --git a/Samples/Blazor/BlazorSample.Shared/ViewModels/HelloWorldViewModel.cs b/Samples/Blazor/BlazorSample.Shared/ViewModels/HelloWorldViewModel.cs
new file mode 100644
index 00000000..c895aa53
--- /dev/null
+++ b/Samples/Blazor/BlazorSample.Shared/ViewModels/HelloWorldViewModel.cs
@@ -0,0 +1,26 @@
+using System.Reactive.Disposables;
+using System.Reactive.Linq;
+using Reactive.Bindings;
+using Reactive.Bindings.Extensions;
+
+namespace BlazorSample.Shared.ViewModels;
+
+public class HelloWorldViewModel : IDisposable
+{
+    private readonly CompositeDisposable _disposable = new();
+
+    public ReactivePropertySlim<string> Input { get; }
+    public ReadOnlyReactivePropertySlim<string> Output { get; }
+
+    public HelloWorldViewModel()
+    {
+        Input = new ReactivePropertySlim<string>("")
+            .AddTo(_disposable);
+        Output = Input
+            .Select(x => x.ToUpperInvariant())
+            .ToReadOnlyReactivePropertySlim("")
+            .AddTo(_disposable);
+    }
+
+    public void Dispose() => _disposable.Dispose();
+}
diff --git a/Samples/Blazor/BlazorSample.Shared/ViewModels/IndexViewModel.cs b/Samples/Blazor/BlazorSample.Shared/ViewModels/ValidationViewModel.cs
similarity index 94%
rename from Samples/Blazor/BlazorSample.Shared/ViewModels/IndexViewModel.cs
rename to Samples/Blazor/BlazorSample.Shared/ViewModels/ValidationViewModel.cs
index 4c716626..2e0ecca0 100644
--- a/Samples/Blazor/BlazorSample.Shared/ViewModels/IndexViewModel.cs
+++ b/Samples/Blazor/BlazorSample.Shared/ViewModels/ValidationViewModel.cs
@@ -6,7 +6,7 @@
 
 namespace BlazorSample.Shared.ViewModels;
 
-public class IndexViewModel : IDisposable
+public class ValidationViewModel : IDisposable
 {
     private readonly CompositeDisposable _disposables = new();
 
@@ -18,7 +18,7 @@ public class IndexViewModel : IDisposable
     public ReactiveProperty<string> LastName { get; }
     public ReadOnlyReactivePropertySlim<string> FullName { get; }
 
-    public IndexViewModel()
+    public ValidationViewModel()
     {
         var reactivePropertyMode = ReactivePropertyMode.Default | ReactivePropertyMode.IgnoreInitialValidationError;
         FirstName = new ReactiveProperty<string>("", mode: reactivePropertyMode)
diff --git a/Samples/Blazor/BlazorServerApp/App.razor b/Samples/Blazor/BlazorServerApp/App.razor
index 5ad7119f..7ea6f775 100644
--- a/Samples/Blazor/BlazorServerApp/App.razor
+++ b/Samples/Blazor/BlazorServerApp/App.razor
@@ -1,5 +1,5 @@
 @using BlazorSample.Shared.ViewModels
-<Router AppAssembly="@typeof(App).Assembly" AdditionalAssemblies="@(new[]{ typeof(IndexViewModel).Assembly })">
+<Router AppAssembly="@typeof(App).Assembly" AdditionalAssemblies="@(new[]{ typeof(ValidationViewModel).Assembly })">
     <Found Context="routeData">
         <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
         <FocusOnNavigate RouteData="@routeData" Selector="h1" />
diff --git a/Samples/Blazor/BlazorServerApp/Program.cs b/Samples/Blazor/BlazorServerApp/Program.cs
index 77a08a6a..ae71739c 100644
--- a/Samples/Blazor/BlazorServerApp/Program.cs
+++ b/Samples/Blazor/BlazorServerApp/Program.cs
@@ -9,7 +9,8 @@
 builder.Services.AddRazorPages();
 builder.Services.AddServerSideBlazor();
 builder.Services.AddSingleton<WeatherForecastService>();
-builder.Services.AddTransient<IndexViewModel>();
+builder.Services.AddTransient<ValidationViewModel>();
+builder.Services.AddTransient<HelloWorldViewModel>();
 
 var app = builder.Build();
 
diff --git a/Samples/Blazor/BlazorWasmApp/App.razor b/Samples/Blazor/BlazorWasmApp/App.razor
index 5ad7119f..7ea6f775 100644
--- a/Samples/Blazor/BlazorWasmApp/App.razor
+++ b/Samples/Blazor/BlazorWasmApp/App.razor
@@ -1,5 +1,5 @@
 @using BlazorSample.Shared.ViewModels
-<Router AppAssembly="@typeof(App).Assembly" AdditionalAssemblies="@(new[]{ typeof(IndexViewModel).Assembly })">
+<Router AppAssembly="@typeof(App).Assembly" AdditionalAssemblies="@(new[]{ typeof(ValidationViewModel).Assembly })">
     <Found Context="routeData">
         <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
         <FocusOnNavigate RouteData="@routeData" Selector="h1" />
diff --git a/Samples/Blazor/BlazorWasmApp/Program.cs b/Samples/Blazor/BlazorWasmApp/Program.cs
index 3ba5bd4d..22be29d8 100644
--- a/Samples/Blazor/BlazorWasmApp/Program.cs
+++ b/Samples/Blazor/BlazorWasmApp/Program.cs
@@ -7,7 +7,8 @@
 builder.RootComponents.Add<App>("#app");
 builder.RootComponents.Add<HeadOutlet>("head::after");
 
-builder.Services.AddTransient<IndexViewModel>();
+builder.Services.AddTransient<ValidationViewModel>();
+builder.Services.AddTransient<HelloWorldViewModel>();
 builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
 
 await builder.Build().RunAsync();
diff --git a/Source/Directory.Build.props b/Source/Directory.Build.props
index 5db16283..ff7dcdec 100644
--- a/Source/Directory.Build.props
+++ b/Source/Directory.Build.props
@@ -1,7 +1,7 @@
 <Project>
   <PropertyGroup>
     <RootNamespace>Reactive.Bindings</RootNamespace>
-    <Version>8.1.0</Version>
+    <Version>8.1.2</Version>
     <Authors>neuecc xin9le okazuki</Authors>
     <PackageProjectUrl>https://github.com/runceel/ReactiveProperty</PackageProjectUrl>
     <PackageTags>rx mvvm async rx-main reactive</PackageTags>
diff --git a/Source/ReactiveProperty.NETStandard/Binding/RxBindingExtensions.cs b/Source/ReactiveProperty.NETStandard/Binding/RxBindingExtensions.cs
index 43d0e51a..357a2e68 100644
--- a/Source/ReactiveProperty.NETStandard/Binding/RxBindingExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/Binding/RxBindingExtensions.cs
@@ -1,4 +1,6 @@
-using System;
+// This namespace is not used almost all cases. low priority to add nullable annnotation.
+#nullable disable
+using System;
 using System.Diagnostics;
 using System.Linq.Expressions;
 using System.Reactive;
@@ -34,11 +36,11 @@ public static IDisposable BindTo<T, TTarget, TProperty>(
         TTarget target,
         Expression<Func<TTarget, TProperty>> propertySelector,
         BindingMode mode = BindingMode.OneWay,
-        Func<T, TProperty>? convert = null,
-        Func<TProperty, T>? convertBack = null,
-        IObservable<Unit>? targetUpdateTrigger = null,
-        TProperty? propertyFallbackValue = default(TProperty),
-        T? sourceFallbackValue = default(T))
+        Func<T, TProperty> convert = null,
+        Func<TProperty, T> convertBack = null,
+        IObservable<Unit> targetUpdateTrigger = null,
+        TProperty propertyFallbackValue = default(TProperty),
+        T sourceFallbackValue = default(T))
     {
         if (convert == null)
         {
@@ -101,8 +103,8 @@ public static IDisposable BindTo<T, TTarget, TProperty>(
         this ReadOnlyReactiveProperty<T> self,
         TTarget target,
         Expression<Func<TTarget, TProperty>> propertySelector,
-        Func<T, TProperty>? convert = null,
-        TProperty? propertyFallbackValue = default(TProperty))
+        Func<T, TProperty> convert = null,
+        TProperty propertyFallbackValue = default(TProperty))
     {
         if (convert == null)
         {
@@ -138,11 +140,11 @@ public static IDisposable BindTo<T, TTarget, TProperty>(
         TTarget target,
         Expression<Func<TTarget, TProperty>> propertySelector,
         BindingMode mode = BindingMode.OneWay,
-        Func<T, TProperty>? convert = null,
-        Func<TProperty, T>? convertBack = null,
-        IObservable<Unit>? targetUpdateTrigger = null,
-        TProperty? propertyFallbackValue = default(TProperty),
-        T? sourceFallbackValue = default(T))
+        Func<T, TProperty> convert = null,
+        Func<TProperty, T> convertBack = null,
+        IObservable<Unit> targetUpdateTrigger = null,
+        TProperty propertyFallbackValue = default(TProperty),
+        T sourceFallbackValue = default(T))
     {
         if (convert == null)
         {
@@ -205,8 +207,8 @@ public static IDisposable BindTo<T, TTarget, TProperty>(
         this ReadOnlyReactivePropertySlim<T> self,
         TTarget target,
         Expression<Func<TTarget, TProperty>> propertySelector,
-        Func<T, TProperty>? convert = null,
-        TProperty? propertyFallbackValue = default(TProperty))
+        Func<T, TProperty> convert = null,
+        TProperty propertyFallbackValue = default(TProperty))
     {
         if (convert == null)
         {
diff --git a/Source/ReactiveProperty.NETStandard/Binding/RxCommandExtensions.cs b/Source/ReactiveProperty.NETStandard/Binding/RxCommandExtensions.cs
index b6c24595..b0a9dd58 100644
--- a/Source/ReactiveProperty.NETStandard/Binding/RxCommandExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/Binding/RxCommandExtensions.cs
@@ -1,4 +1,6 @@
-using System;
+// This namespace is not used almost all cases. low priority to add nullable annnotation.
+#nullable disable
+using System;
 
 namespace Reactive.Bindings.Binding;
 
diff --git a/Source/ReactiveProperty.NETStandard/Extensions/INotifyCollectionChangedExtensions.cs b/Source/ReactiveProperty.NETStandard/Extensions/INotifyCollectionChangedExtensions.cs
index 776d0150..2bd56876 100644
--- a/Source/ReactiveProperty.NETStandard/Extensions/INotifyCollectionChangedExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/Extensions/INotifyCollectionChangedExtensions.cs
@@ -12,6 +12,9 @@
 
 namespace Reactive.Bindings.Extensions;
 
+// TODO: remove this line later.
+#nullable disable
+
 /// <summary>
 /// INotify Collection Changed Extensions
 /// </summary>
@@ -49,7 +52,7 @@ public static IObservable<T[]> ObserveAddChangedItems<T>(this INotifyCollectionC
     public static IObservable<T> ObserveRemoveChanged<T>(this INotifyCollectionChanged source) =>
         source.CollectionChangedAsObservable()
             .Where(e => e.Action == NotifyCollectionChangedAction.Remove)
-            .Select(e => (T)e.OldItems[0]);
+            .Select(e => (T)e.OldItems[0]!);
 
     /// <summary>
     /// Observe CollectionChanged:Remove.
diff --git a/Source/ReactiveProperty.NETStandard/Extensions/INotifyPropertyChangedExtensions.cs b/Source/ReactiveProperty.NETStandard/Extensions/INotifyPropertyChangedExtensions.cs
index 459c57dd..400cfd6a 100644
--- a/Source/ReactiveProperty.NETStandard/Extensions/INotifyPropertyChangedExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/Extensions/INotifyPropertyChangedExtensions.cs
@@ -116,8 +116,7 @@ public static ReactiveProperty<TProperty> ToReactivePropertyAsSynchronized<TSubj
         {
             var observer = PropertyObservable.CreateFromPropertySelector(subject, propertySelector);
             var result = Observable.Using(() => observer, x => x)
-                .StartWith(observer.GetPropertyPathValue())
-                .ToReactiveProperty(raiseEventScheduler, mode: mode);
+                .ToReactiveProperty(raiseEventScheduler, initialValue: observer.GetPropertyPathValue(), mode: mode);
             result
                 .Where(_ => !ignoreValidationErrorValue || !result.HasErrors)
                 .Subscribe(x => observer.SetPropertyPathValue(x));
@@ -125,8 +124,9 @@ public static ReactiveProperty<TProperty> ToReactivePropertyAsSynchronized<TSubj
         }
         else
         {
-            var result = subject.ObserveSimpleProperty(propertySelector, isPushCurrentValueAtFirst: true)
-                .ToReactiveProperty(raiseEventScheduler, mode: mode);
+            var getter = AccessorCache<TSubject>.LookupGet(propertySelector, out var _);
+            var result = subject.ObserveSimpleProperty(propertySelector, isPushCurrentValueAtFirst: false)
+                .ToReactiveProperty(raiseEventScheduler, initialValue: getter(subject), mode: mode);
             var setter = AccessorCache<TSubject>.LookupSet(propertySelector, out _);
             result
                 .Where(_ => !ignoreValidationErrorValue || !result.HasErrors)
@@ -244,7 +244,7 @@ public static ReactiveProperty<TResult> ToReactivePropertyAsSynchronized<TSubjec
             var observer = PropertyObservable.CreateFromPropertySelector(subject, propertySelector);
             var result = convert(Observable.Using(() => observer, x => x)
                 .StartWith(observer.GetPropertyPathValue()))
-                .ToReactiveProperty(raiseEventScheduler, mode: mode);
+                .ToReactiveProperty<TResult>(raiseEventScheduler, mode: mode);
             convertBack(result.Where(_ => !ignoreValidationErrorValue || !result.HasErrors))
                .Subscribe(x => observer.SetPropertyPathValue(x));
             return result;
@@ -253,7 +253,7 @@ public static ReactiveProperty<TResult> ToReactivePropertyAsSynchronized<TSubjec
         {
             var setter = AccessorCache<TSubject>.LookupSet(propertySelector, out _);
             var result = convert(subject.ObserveProperty(propertySelector, isPushCurrentValueAtFirst: true))
-                .ToReactiveProperty(raiseEventScheduler, mode: mode);
+                .ToReactiveProperty<TResult>(raiseEventScheduler, mode: mode);
             convertBack(result.Where(_ => !ignoreValidationErrorValue || !result.HasErrors))
                 .Subscribe(x => setter(subject, x));
             return result;
@@ -347,8 +347,7 @@ public static ReactivePropertySlim<TResult> ToReactivePropertySlimAsSynchronized
         {
             var result = new ReactivePropertySlim<TResult>(mode: mode);
             var observer = PropertyObservable.CreateFromPropertySelector(subject, propertySelector);
-            IDisposable disposable = null;
-            disposable = convert(subject.ObserveProperty(propertySelector, isPushCurrentValueAtFirst: true))
+            var disposable = convert(subject.ObserveProperty(propertySelector, isPushCurrentValueAtFirst: true))
                 .Subscribe(x => result.Value = x);
             convertBack(result)
                 .Subscribe(x => observer.SetPropertyPathValue(x), _ => disposable.Dispose(), () => disposable.Dispose());
@@ -358,8 +357,7 @@ public static ReactivePropertySlim<TResult> ToReactivePropertySlimAsSynchronized
         {
             var setter = AccessorCache<TSubject>.LookupSet(propertySelector, out _);
             var result = new ReactivePropertySlim<TResult>(mode: mode);
-            IDisposable disposable = null;
-            disposable = convert(subject.ObserveProperty(propertySelector, isPushCurrentValueAtFirst: true))
+            var disposable = convert(subject.ObserveProperty(propertySelector, isPushCurrentValueAtFirst: true))
                 .Subscribe(x => result.Value = x);
             convertBack(result)
                 .Subscribe(x => setter(subject, x), _ => disposable.Dispose(), () => disposable.Dispose());
diff --git a/Source/ReactiveProperty.NETStandard/Extensions/PairwiseObservableExtensions.cs b/Source/ReactiveProperty.NETStandard/Extensions/PairwiseObservableExtensions.cs
index b808faad..d3576492 100644
--- a/Source/ReactiveProperty.NETStandard/Extensions/PairwiseObservableExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/Extensions/PairwiseObservableExtensions.cs
@@ -21,7 +21,7 @@ public static IObservable<TR> Pairwise<T, TR>(this IObservable<T> source, Func<T
     {
         var result = Observable.Create<TR>(observer =>
         {
-            var prev = default(T);
+            T prev = default!;
             var isFirst = true;
 
             return source.Subscribe(x =>
@@ -36,7 +36,7 @@ public static IObservable<TR> Pairwise<T, TR>(this IObservable<T> source, Func<T
                 TR value;
                 try
                 {
-                    value = selector(prev, x);
+                    value = selector(prev!, x);
                     prev = x;
                 }
                 catch (Exception ex)
diff --git a/Source/ReactiveProperty.NETStandard/Extensions/RetryObservableExtensions.cs b/Source/ReactiveProperty.NETStandard/Extensions/RetryObservableExtensions.cs
index fb743868..0835ec4d 100644
--- a/Source/ReactiveProperty.NETStandard/Extensions/RetryObservableExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/Extensions/RetryObservableExtensions.cs
@@ -64,14 +64,14 @@ public static IObservable<TSource> OnErrorRetry<TSource, TException>(
             var empty = Observable.Empty<TSource>();
             var count = 0;
 
-            IObservable<TSource>? self = null;
+            IObservable<TSource> self = null!;
             self = source.Catch((TException ex) =>
             {
                 onError(ex);
 
                 return (++count < retryCount)
                     ? (dueTime == TimeSpan.Zero)
-                        ? self!.SubscribeOn(Scheduler.CurrentThread)
+                        ? self.SubscribeOn(Scheduler.CurrentThread)
                         : empty.Delay(dueTime, delayScheduler).Concat(self).SubscribeOn(Scheduler.CurrentThread)
                     : Observable.Throw<TSource>(ex);
             });
diff --git a/Source/ReactiveProperty.NETStandard/Helpers/CollectionUtilities.cs b/Source/ReactiveProperty.NETStandard/Helpers/CollectionUtilities.cs
index cc693276..01672d09 100644
--- a/Source/ReactiveProperty.NETStandard/Helpers/CollectionUtilities.cs
+++ b/Source/ReactiveProperty.NETStandard/Helpers/CollectionUtilities.cs
@@ -86,8 +86,9 @@ public static IObservable<PropertyPack<TElement, TProperty>> ObserveElementObser
         if (!(propertySelector.Body is MemberExpression memberExpression))
         {
             if (!(propertySelector.Body is UnaryExpression unaryExpression)) { throw new ArgumentException(nameof(propertySelector)); }
-            memberExpression = unaryExpression.Operand as MemberExpression;
-            if (memberExpression == null) { throw new ArgumentException(nameof(propertySelector)); }
+            var operand = unaryExpression.Operand as MemberExpression;
+            if (operand == null) { throw new ArgumentException(nameof(propertySelector)); }
+            memberExpression = operand;
         }
 
         var propertyInfo = memberExpression.Member as PropertyInfo;
@@ -154,11 +155,11 @@ internal static IObservable<TResult> ObserveElementCore<TCollection, TElement, T
     {
         return Observable.Create<TResult>(observer =>
         {
-                //--- cache element property subscriptions
-                var subscriptionCache = new Dictionary<object, IDisposable>();
+            //--- cache element property subscriptions
+            var subscriptionCache = new Dictionary<object, IDisposable>();
 
-                //--- subscribe / unsubscribe property which all elements have
-                void subscribe(IEnumerable<TElement> elements)
+            //--- subscribe / unsubscribe property which all elements have
+            void subscribe(IEnumerable<TElement> elements)
             {
                 foreach (var x in elements)
                 {
@@ -177,14 +178,14 @@ void unsubscribeAll()
             }
             subscribe(source);
 
-                //--- hook collection changed
-                var disposable = source.CollectionChangedAsObservable().Subscribe(x =>
+            //--- hook collection changed
+            var disposable = source.CollectionChangedAsObservable().Subscribe(x =>
             {
                 if (x.Action == NotifyCollectionChangedAction.Remove
                 || x.Action == NotifyCollectionChangedAction.Replace)
                 {
-                        //--- unsubscribe
-                        var oldItems = x.OldItems.Cast<TElement>();
+                    //--- unsubscribe
+                    var oldItems = x.OldItems.Cast<TElement>();
                     foreach (var y in oldItems)
                     {
                         subscriptionCache[y].Dispose();
@@ -206,8 +207,8 @@ void unsubscribeAll()
                 }
             });
 
-                //--- unsubscribe
-                return Disposable.Create(() =>
+            //--- unsubscribe
+            return Disposable.Create(() =>
             {
                 disposable.Dispose();
                 unsubscribeAll();
diff --git a/Source/ReactiveProperty.NETStandard/Helpers/FilteredReadOnlyObservableCollection.cs b/Source/ReactiveProperty.NETStandard/Helpers/FilteredReadOnlyObservableCollection.cs
index 221b4611..f2febb17 100644
--- a/Source/ReactiveProperty.NETStandard/Helpers/FilteredReadOnlyObservableCollection.cs
+++ b/Source/ReactiveProperty.NETStandard/Helpers/FilteredReadOnlyObservableCollection.cs
@@ -86,14 +86,14 @@ public FilteredReadOnlyObservableCollection(TCollection source, Func<TElement, b
             Initialize();
         }
 
+        // collection changed(support single changed only)
+        source.CollectionChanged += Source_CollectionChanged;
+
         // propertychanged
         CollectionUtilities.ObserveElementCore<TCollection, TElement, TElement>(source, (x, observer) =>
             elementChangedFactory(x).Subscribe(_ => observer.OnNext(x)))
             .Subscribe(SourceElementChanged)
             .AddTo(Subscription);
-
-        // collection changed(support single changed only)
-        source.CollectionChanged += Source_CollectionChanged;
     }
 
     private void SourceElementChanged(TElement x)
diff --git a/Source/ReactiveProperty.NETStandard/Interactivity/IEventToReactiveConverter.cs b/Source/ReactiveProperty.NETStandard/Interactivity/IEventToReactiveConverter.cs
index 14bbfe65..f3bc14c3 100644
--- a/Source/ReactiveProperty.NETStandard/Interactivity/IEventToReactiveConverter.cs
+++ b/Source/ReactiveProperty.NETStandard/Interactivity/IEventToReactiveConverter.cs
@@ -14,12 +14,12 @@ public interface IEventToReactiveConverter
     /// Gets or sets the associate object.
     /// </summary>
     /// <value>The associate object.</value>
-    object AssociateObject { get; set; }
+    object? AssociateObject { get; set; }
 
     /// <summary>
     /// Converts the specified source.
     /// </summary>
     /// <param name="source">The source.</param>
     /// <returns></returns>
-    IObservable<object> Convert(IObservable<object> source);
+    IObservable<object?> Convert(IObservable<object?> source);
 }
diff --git a/Source/ReactiveProperty.NETStandard/Interactivity/ReactiveConverter.cs b/Source/ReactiveProperty.NETStandard/Interactivity/ReactiveConverter.cs
index 5ac40a96..eb77fa81 100644
--- a/Source/ReactiveProperty.NETStandard/Interactivity/ReactiveConverter.cs
+++ b/Source/ReactiveProperty.NETStandard/Interactivity/ReactiveConverter.cs
@@ -17,19 +17,19 @@ public abstract class ReactiveConverter<T, U> : IEventToReactiveConverter
     /// <summary>
     /// EventToReactiveCommand's AssociateObject
     /// </summary>
-    public object AssociateObject { get; set; }
+    public object? AssociateObject { get; set; }
 
     /// <summary>
     /// Converts the specified source.
     /// </summary>
     /// <param name="source">The source.</param>
     /// <returns></returns>
-    public IObservable<object> Convert(IObservable<object> source) => OnConvert(source.Cast<T>()).Select(x => (object)x);
+    public IObservable<object?> Convert(IObservable<object?> source) => OnConvert(source.Select(x => (T?)x)).Select(x => (object?)x);
 
     /// <summary>
     /// Converts
     /// </summary>
     /// <param name="source">source</param>
     /// <returns>dest</returns>
-    protected abstract IObservable<U> OnConvert(IObservable<T> source);
+    protected abstract IObservable<U?> OnConvert(IObservable<T?> source);
 }
diff --git a/Source/ReactiveProperty.NETStandard/Internals/PropertyObservable.cs b/Source/ReactiveProperty.NETStandard/Internals/PropertyObservable.cs
index 13709568..1ed30b28 100644
--- a/Source/ReactiveProperty.NETStandard/Internals/PropertyObservable.cs
+++ b/Source/ReactiveProperty.NETStandard/Internals/PropertyObservable.cs
@@ -7,7 +7,7 @@ namespace Reactive.Bindings.Internals;
 
 internal sealed class PropertyObservable<TProperty> : IObservable<TProperty>, IDisposable
 {
-    private PropertyPathNode RootNode { get; set; }
+    private PropertyPathNode? RootNode { get; set; }
     internal void SetRootNode(PropertyPathNode rootNode)
     {
         RootNode?.SetCallback(null);
@@ -17,7 +17,7 @@ internal void SetRootNode(PropertyPathNode rootNode)
     public TProperty GetPropertyPathValue()
     {
         var value = RootNode?.GetPropertyPathValue();
-        return value != null ? (TProperty)value : default;
+        return value != null ? (TProperty)value : default!;
     }
 
     public string Path => RootNode?.Path;
diff --git a/Source/ReactiveProperty.NETStandard/Internals/PropertyPathNode.cs b/Source/ReactiveProperty.NETStandard/Internals/PropertyPathNode.cs
index 6a5888b4..e5c66344 100644
--- a/Source/ReactiveProperty.NETStandard/Internals/PropertyPathNode.cs
+++ b/Source/ReactiveProperty.NETStandard/Internals/PropertyPathNode.cs
@@ -24,7 +24,7 @@ public PropertyPathNode(string propertyName)
     private Type? PrevSourceType { get; set; }
     public PropertyPathNode? Next { get; private set; }
     public PropertyPathNode? Prev { get; private set; }
-    public void SetCallback(Action callback)
+    public void SetCallback(Action? callback)
     {
         _callback = callback;
         Next?.SetCallback(callback);
diff --git a/Source/ReactiveProperty.NETStandard/ReactiveProperty.cs b/Source/ReactiveProperty.NETStandard/ReactiveProperty.cs
index b3b518f5..62983a5b 100644
--- a/Source/ReactiveProperty.NETStandard/ReactiveProperty.cs
+++ b/Source/ReactiveProperty.NETStandard/ReactiveProperty.cs
@@ -82,7 +82,7 @@ public class ReactiveProperty<T> : IReactiveProperty<T>, IObserverLinkedList<T>
 
     private Lazy<BehaviorSubject<IEnumerable?>> ErrorsTrigger { get; }
 
-    private Lazy<List<Func<IObservable<T>, IObservable<IEnumerable>>>> ValidatorStore { get; } = new Lazy<List<Func<IObservable<T>, IObservable<IEnumerable>>>>(() => new List<Func<IObservable<T>, IObservable<IEnumerable>>>());
+    private Lazy<List<Func<IObservable<T>, IObservable<IEnumerable?>>>> ValidatorStore { get; } = new Lazy<List<Func<IObservable<T>, IObservable<IEnumerable?>>>>(() => new List<Func<IObservable<T>, IObservable<IEnumerable?>>>());
 
     /// <summary>
     /// PropertyChanged raise on ReactivePropertyScheduler
@@ -283,7 +283,7 @@ public override string ToString() =>
     /// </summary>
     /// <param name="validator">If success return IO&lt;null&gt;, failure return IO&lt;IEnumerable&gt;(Errors).</param>
     /// <returns>Self.</returns>
-    public ReactiveProperty<T> SetValidateNotifyError(Func<IObservable<T>, IObservable<IEnumerable>> validator)
+    public ReactiveProperty<T> SetValidateNotifyError(Func<IObservable<T>, IObservable<IEnumerable?>> validator)
     {
         ValidatorStore.Value.Add(validator);     //--- cache validation functions
         var validators = ValidatorStore.Value
@@ -304,12 +304,12 @@ public ReactiveProperty<T> SetValidateNotifyError(Func<IObservable<T>, IObservab
                 }
 
                 var strings = xs
-                    .OfType<string>()
-                    .Where(x => x != null);
+                    .Where(x => x != null)
+                    .OfType<string>();
                 var others = xs
-                    .Where(x => !(x is string))
+                    .Where(x => x is not string)
                     .Where(x => x != null)
-                    .SelectMany(x => x.Cast<object>());
+                    .SelectMany(x => x!.Cast<object?>());
                 return strings.Concat(others);
             })
             .Subscribe(x =>
@@ -339,15 +339,15 @@ public ReactiveProperty<T> SetValidateNotifyError(Func<IObservable<T>, IObservab
     /// </summary>
     /// <param name="validator">If success return IO&lt;null&gt;, failure return IO&lt;IEnumerable&gt;(Errors).</param>
     /// <returns>Self.</returns>
-    public ReactiveProperty<T> SetValidateNotifyError(Func<IObservable<T>, IObservable<string>> validator) =>
-        SetValidateNotifyError(xs => validator(xs).Cast<IEnumerable>());
+    public ReactiveProperty<T> SetValidateNotifyError(Func<IObservable<T>, IObservable<string?>> validator) =>
+        SetValidateNotifyError(xs => validator(xs).Select(x => (IEnumerable?)x));
 
     /// <summary>
     /// Set INotifyDataErrorInfo's asynchronous validation.
     /// </summary>
     /// <param name="validator">Validation logic</param>
     /// <returns>Self.</returns>
-    public ReactiveProperty<T> SetValidateNotifyError(Func<T, Task<IEnumerable>> validator) =>
+    public ReactiveProperty<T> SetValidateNotifyError(Func<T, Task<IEnumerable?>> validator) =>
         SetValidateNotifyError(xs => xs.SelectMany(x => validator(x)));
 
     /// <summary>
@@ -355,7 +355,7 @@ public ReactiveProperty<T> SetValidateNotifyError(Func<T, Task<IEnumerable>> val
     /// </summary>
     /// <param name="validator">Validation logic</param>
     /// <returns>Self.</returns>
-    public ReactiveProperty<T> SetValidateNotifyError(Func<T, Task<string>> validator) =>
+    public ReactiveProperty<T> SetValidateNotifyError(Func<T, Task<string?>> validator) =>
         SetValidateNotifyError(xs => xs.SelectMany(x => validator(x)));
 
     /// <summary>
@@ -363,7 +363,7 @@ public ReactiveProperty<T> SetValidateNotifyError(Func<T, Task<string>> validato
     /// </summary>
     /// <param name="validator">Validation logic</param>
     /// <returns>Self.</returns>
-    public ReactiveProperty<T> SetValidateNotifyError(Func<T, IEnumerable> validator) =>
+    public ReactiveProperty<T> SetValidateNotifyError(Func<T, IEnumerable?> validator) =>
         SetValidateNotifyError(xs => xs.Select(x => validator(x)));
 
     /// <summary>
@@ -371,7 +371,7 @@ public ReactiveProperty<T> SetValidateNotifyError(Func<T, IEnumerable> validator
     /// </summary>
     /// <param name="validator">Validation logic</param>
     /// <returns>Self.</returns>
-    public ReactiveProperty<T> SetValidateNotifyError(Func<T, string> validator) =>
+    public ReactiveProperty<T> SetValidateNotifyError(Func<T, string?> validator) =>
         SetValidateNotifyError(xs => xs.Select(x => validator(x)));
 
     /// <summary>
diff --git a/Source/ReactiveProperty.NETStandard/ReactivePropertyExtensions.cs b/Source/ReactiveProperty.NETStandard/ReactivePropertyExtensions.cs
index a5bf0611..851f8b43 100644
--- a/Source/ReactiveProperty.NETStandard/ReactivePropertyExtensions.cs
+++ b/Source/ReactiveProperty.NETStandard/ReactivePropertyExtensions.cs
@@ -20,7 +20,7 @@ public static class ReactivePropertyExtensions
     /// <param name="self">Target ReactiveProperty</param>
     /// <param name="selfSelector">Target property as expression</param>
     /// <returns>Self</returns>
-    public static ReactiveProperty<T> SetValidateAttribute<T>(this ReactiveProperty<T> self, Expression<Func<ReactiveProperty<T>>> selfSelector)
+    public static ReactiveProperty<T> SetValidateAttribute<T>(this ReactiveProperty<T> self, Expression<Func<ReactiveProperty<T>?>> selfSelector)
     {
         var memberExpression = (MemberExpression)selfSelector.Body;
         var propertyInfo = (PropertyInfo)memberExpression.Member;
@@ -54,7 +54,7 @@ public static ReactiveProperty<T> SetValidateAttribute<T>(this ReactiveProperty<
     /// </summary>
     /// <typeparam name="T">Property type</typeparam>
     /// <param name="self">Target ReactiveProperty</param>
-    public static IObservable<string> ObserveValidationErrorMessage<T>(this ReactiveProperty<T> self) =>
+    public static IObservable<string?> ObserveValidationErrorMessage<T>(this ReactiveProperty<T> self) =>
         self.ObserveErrorChanged
             .Select(x => x?.OfType<string>()?.FirstOrDefault());
 }
diff --git a/Source/ReactiveProperty.Platform.Android/ListAdapter.cs b/Source/ReactiveProperty.Platform.Android/ListAdapter.cs
index 9ec0d224..827c9f6b 100644
--- a/Source/ReactiveProperty.Platform.Android/ListAdapter.cs
+++ b/Source/ReactiveProperty.Platform.Android/ListAdapter.cs
@@ -26,7 +26,7 @@ public class ListAdapter<T> : BaseAdapter<T>
     /// <param name="createRowView">create view</param>
     /// <param name="setRowData">set row data</param>
     /// <param name="getId">get id</param>
-    public ListAdapter(IList<T> list, Func<int, T, View> createRowView, Action<int, T, View> setRowData, Func<int, T, long>? getId = null)
+    public ListAdapter(IList<T> list, Func<int, T, View> createRowView, Action<int, T, View> setRowData, Func<int, T, long> getId = null)
     {
         List = list ?? throw new ArgumentNullException(nameof(list));
         CreateRowView = createRowView ?? throw new ArgumentNullException(nameof(createRowView));
@@ -65,7 +65,7 @@ public ListAdapter(IList<T> list, Func<int, T, View> createRowView, Action<int,
     /// <param name="parent">To be added.</param>
     /// <returns>To be added.</returns>
     /// <remarks>To be added.</remarks>
-    public override View GetView(int position, View? convertView, ViewGroup? parent)
+    public override View GetView(int position, View convertView, ViewGroup parent)
     {
         if (convertView == null)
         {
@@ -91,6 +91,6 @@ public static class ListExtensions
     /// <param name="setRowData">fill row data</param>
     /// <param name="getId">get id</param>
     /// <returns>ListAdapter</returns>
-    public static ListAdapter<T> ToAdapter<T>(this IList<T> self, Func<int, T, View> createRowView, Action<int, T, View> setRowData, Func<int, T, long>? getId = null) =>
+    public static ListAdapter<T> ToAdapter<T>(this IList<T> self, Func<int, T, View> createRowView, Action<int, T, View> setRowData, Func<int, T, long> getId = null) =>
         new(self, createRowView, setRowData, getId);
 }
diff --git a/Source/ReactiveProperty.Platform.Android/ReactiveProperty.Platform.Android.csproj b/Source/ReactiveProperty.Platform.Android/ReactiveProperty.Platform.Android.csproj
index 3e5e9c81..219d3c5d 100644
--- a/Source/ReactiveProperty.Platform.Android/ReactiveProperty.Platform.Android.csproj
+++ b/Source/ReactiveProperty.Platform.Android/ReactiveProperty.Platform.Android.csproj
@@ -7,6 +7,7 @@
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>key.snk</AssemblyOriginatorKeyFile>
     <Description>ReactiveProperty.XamarinAndroid provides many useful extension methods for Xamarin.Android that can be used with ReactiveProperty.</Description>
+    <Nullable>disable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\ReactiveProperty.NETStandard\ReactiveProperty.NETStandard.csproj" />
diff --git a/Source/ReactiveProperty.Platform.iOS/ReactiveProperty.Platform.iOS.csproj b/Source/ReactiveProperty.Platform.iOS/ReactiveProperty.Platform.iOS.csproj
index cd902632..f455f7ed 100644
--- a/Source/ReactiveProperty.Platform.iOS/ReactiveProperty.Platform.iOS.csproj
+++ b/Source/ReactiveProperty.Platform.iOS/ReactiveProperty.Platform.iOS.csproj
@@ -7,6 +7,7 @@
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>key.snk</AssemblyOriginatorKeyFile>
     <Description>ReactiveProperty.XamariniOS provides many useful extension methods for Xamarin.iOS that can be used with ReactiveProperty.</Description>
+    <Nullable>disable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\ReactiveProperty.NETStandard\ReactiveProperty.NETStandard.csproj" />
diff --git a/Test/ReactiveProperty.NETStandard.Tests/Helpers/FilteredReadOnlyObservableCollectionTest.cs b/Test/ReactiveProperty.NETStandard.Tests/Helpers/FilteredReadOnlyObservableCollectionTest.cs
index 03420bc8..673eb502 100644
--- a/Test/ReactiveProperty.NETStandard.Tests/Helpers/FilteredReadOnlyObservableCollectionTest.cs
+++ b/Test/ReactiveProperty.NETStandard.Tests/Helpers/FilteredReadOnlyObservableCollectionTest.cs
@@ -462,6 +462,23 @@ public void NestedPropertyCase()
         filtered.Select(x => x.Name).Is("tanaka2", "tanaka3", "tanaka4", "tanaka5");
     }
 
+    [TestMethod]
+    public void ElementStatusChangedFactoryWithObservePropertyTest()
+    {
+        // https://github.com/runceel/ReactiveProperty/issues/379
+        var observableCollection = new ObservableCollection<Person>();
+
+        var filteredCollection = observableCollection.ToFilteredReadOnlyObservableCollection(
+            filter: x => x.Name == "test",
+            elementStatusChangedFactory: x => x.ObserveProperty(x => x.Name));
+
+        AssertEx.DoesNotThrow(() =>
+        {
+            var element = new Person();
+            observableCollection.Add(element); // Exception thrown here (Issue 379)
+        });
+    }
+
     private class Person : INotifyPropertyChanged
     {
         public event PropertyChangedEventHandler PropertyChanged;
diff --git a/docs/docs/.vuepress/config.js b/docs/docs/.vuepress/config.js
index bd4eff9f..c4e14de6 100644
--- a/docs/docs/.vuepress/config.js
+++ b/docs/docs/.vuepress/config.js
@@ -14,6 +14,7 @@ module.exports = {
                     { text: 'Xamarin.Forms', link: '/getting-started/xf.html' },
                     { text: 'Avalonia', link: '/getting-started/avalonia.html' },
                     { text: 'Uno Platform', link: '/getting-started/uno-platform.html' },
+                    { text: 'Blazor', link: '/getting-started/blazor.html' },
                     { text: 'Add code snippets', link: '/getting-started/add-snippets.html' },
                 ]
             },
diff --git a/docs/docs/getting-started/blazor.md b/docs/docs/getting-started/blazor.md
new file mode 100644
index 00000000..e3633113
--- /dev/null
+++ b/docs/docs/getting-started/blazor.md
@@ -0,0 +1,126 @@
+# Getting start for Blazor
+
+Blazor is for development framework for Single Page Application using C#.
+
+See below:
+
+[ASP.NET Core Blazor](https://docs.microsoft.com/en-us/aspnet/core/blazor/)
+
+ReactiveProperty also works both of Blazor Server and Blazor WebAssembly. But Blazor WebAssembly doen't support all operations of Reactive Extensions. For example, `Delay` extension method doesn't work on Blazor WASM.
+If you want to use ReactiveProperty on Blazor WASM, then please care to not use unsupported features. 
+
+## Create a project
+
+- Create a Blazor Server or WebAssembly project.
+- Install ReactiveProperty.Blazor package from NuGet.
+
+## Edit codes
+
+- Create a class what name is `IndexViewModel`.
+- Edit the class like fillowing:
+
+```csharp
+using Reactive.Bindings;
+using Reactive.Bindings.Extensions;
+using System.Reactive.Disposables;
+using System.Reactive.Linq;
+
+namespace BlazorApp1;
+
+public class IndexViewModel : IDisposable
+{
+    private CompositeDisposable _disposable = new();
+
+    public ReactivePropertySlim<string> Input { get; }
+    public ReadOnlyReactivePropertySlim<string> Output { get; }
+
+    public IndexViewModel()
+    {
+        Input = new ReactivePropertySlim<string>("")
+            .AddTo(_disposable);
+        Output = Input
+            .Delay(TimeSpan.FromSeconds(2)) // Important! Delay method doesn't work on Blazor WASM. If you are working on WASM, then please remove this line.
+            .Select(x => x.ToUpperInvariant())
+            .ToReadOnlyReactivePropertySlim("")
+            .AddTo(_disposable);
+    }
+
+    public void Dispose() => _disposable.Dispose();
+}
+```
+
+- Edit Index.razor like below:
+
+```csharp
+@page "/"
+@using System.Reactive.Disposables
+@using Reactive.Bindings.Extensions
+@implements IDisposable
+
+<PageTitle>Index</PageTitle>
+
+<h1>Hello, world!</h1>
+
+<input type="text" @bind="_viewModel.Input.Value" />
+<br/>
+@_viewModel.Output.Value
+<br/>
+
+@code {
+    private readonly CompositeDisposable _disposable = new();
+    private IndexViewModel _viewModel = default!;
+
+    protected override void OnInitialized()
+    {
+        _viewModel = new IndexViewModel()
+            .AddTo(_disposable);
+
+        // Observe changing Output property, and call StateHasChanged on UI thread.
+        _viewModel.Output
+            .Subscribe(x => InvokeAsync(StateHasChanged))
+            .AddTo(_disposable);
+    }
+
+    public void Dispose() => _disposable.Dispose();
+}
+```
+
+- Launch this app
+
+You can see below result:
+
+![Launch the app](./images/blazor-helloworld.png)
+
+## Other topics for Blazor
+
+### Dependency Injection
+
+If you want to inject ViewModels to page, then please register ViewModels to DI container on Program.cs like below:
+
+```csharp
+builder.Services.AddTransient<IndexViewModel>();
+```
+
+And inject to page like `@inject IndexViewModel _viewModel`.
+
+
+### Integrate validation feature
+
+If you want to use validation feature of ReactiveProperty with Blazor's EditForm component, then you can use `Reactive.Bindings.Components.ReactivePropertiesValidator` component.
+
+`ReactivePropertiesValidator` can be used same as `DataAnnotationsValidator` component like below:
+
+```csharp
+<EditForm Model="_validationViewModel" OnInvalidSubmit="InvalidSubmit" OnValidSubmit="ValidSubmit">
+    <ReactivePropertiesValidator /> @* needs @using Reactive.Bindings.Components *@
+
+    <ValidationSummary />
+
+    <div class="mb-3">
+        <label for="firstName">First name</label>
+        <InputText @bind-Value="_validationViewModel.FirstName.Value" class="form-control" />
+        <ValidationMessage For="() => _validationViewModel.FirstName.Value" />
+    </div>
+```
+
+Please see Blazor's sample app under Samples/Blazor folder to know more details. The page using it is Pages/Index.razor page of BlazorSample.Shared project.
diff --git a/docs/docs/getting-started/images/blazor-helloworld.png b/docs/docs/getting-started/images/blazor-helloworld.png
new file mode 100644
index 00000000..ba2df8f6
Binary files /dev/null and b/docs/docs/getting-started/images/blazor-helloworld.png differ
diff --git a/docs/package-lock.json b/docs/package-lock.json
index bc34ef09..cabf966d 100644
--- a/docs/package-lock.json
+++ b/docs/package-lock.json
@@ -1975,9 +1975,9 @@
       "dev": true
     },
     "async": {
-      "version": "2.6.3",
-      "resolved": "https://registry.npmjs.org/async/-/async-2.6.3.tgz",
-      "integrity": "sha512-zflvls11DCy+dQWzTW2dzuilv8Z5X/pjfmZOWba6TNIVDm+2UDaJmXSOXlasHKfNBs8oo3M0aT50fDEWfKZjXg==",
+      "version": "2.6.4",
+      "resolved": "https://registry.npmjs.org/async/-/async-2.6.4.tgz",
+      "integrity": "sha512-mzo5dfJYwAn29PeiJ0zvwTo04zj8HDJj0Mn8TD7sno7q12prdbnasKJHhkm2c1LgrhlJ0teaea8860oxi51mGA==",
       "dev": true,
       "requires": {
         "lodash": "^4.17.14"
@@ -4247,9 +4247,9 @@
       "dev": true
     },
     "eventsource": {
-      "version": "1.0.7",
-      "resolved": "https://registry.npmjs.org/eventsource/-/eventsource-1.0.7.tgz",
-      "integrity": "sha512-4Ln17+vVT0k8aWq+t/bF5arcS3EpT9gYtW66EPacdj/mAFevznsnyoHLPy2BA8gbIQeIHoPsvwmfBftfcG//BQ==",
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/eventsource/-/eventsource-1.1.1.tgz",
+      "integrity": "sha512-qV5ZC0h7jYIAOhArFJgSfdyz6rALJyb270714o7ZtNnw2WSJ+eexhKtE0O8LYPRsHZHf2osHKZBxGPvm3kPkCA==",
       "dev": true,
       "requires": {
         "original": "^1.0.0"