diff --git a/src/Polly.Core/CircuitBreaker/CircuitBreakerManualControl.cs b/src/Polly.Core/CircuitBreaker/CircuitBreakerManualControl.cs
index 1258c4f5ae4..4eca9c8c355 100644
--- a/src/Polly.Core/CircuitBreaker/CircuitBreakerManualControl.cs
+++ b/src/Polly.Core/CircuitBreaker/CircuitBreakerManualControl.cs
@@ -148,7 +148,7 @@ public async Task CloseAsync(CancellationToken cancellationToken = default)
         }
     }
 
-    private class RegistrationDisposable : IDisposable
+    private sealed class RegistrationDisposable : IDisposable
     {
         private readonly Action _disposeAction;
 
diff --git a/src/Polly.Core/CircuitBreaker/Controller/ScheduledTaskExecutor.cs b/src/Polly.Core/CircuitBreaker/Controller/ScheduledTaskExecutor.cs
index 7bc3f6f6d5f..a379949f38c 100644
--- a/src/Polly.Core/CircuitBreaker/Controller/ScheduledTaskExecutor.cs
+++ b/src/Polly.Core/CircuitBreaker/Controller/ScheduledTaskExecutor.cs
@@ -84,5 +84,5 @@ private async Task StartProcessingAsync()
         }
     }
 
-    private record Entry(Func<Task> TaskFactory, bool ContinueOnCapturedContext, TaskCompletionSource<object> TaskCompletion);
+    private sealed record Entry(Func<Task> TaskFactory, bool ContinueOnCapturedContext, TaskCompletionSource<object> TaskCompletion);
 }
diff --git a/src/Polly.Core/Registry/RegistryPipelineComponentBuilder.cs b/src/Polly.Core/Registry/RegistryPipelineComponentBuilder.cs
index fb826066e7d..848cd6eaeeb 100644
--- a/src/Polly.Core/Registry/RegistryPipelineComponentBuilder.cs
+++ b/src/Polly.Core/Registry/RegistryPipelineComponentBuilder.cs
@@ -6,7 +6,7 @@ namespace Polly.Registry;
 /// <summary>
 /// Builds a <see cref="PipelineComponent"/> used by the registry.
 /// </summary>
-internal class RegistryPipelineComponentBuilder<TBuilder, TKey>
+internal sealed class RegistryPipelineComponentBuilder<TBuilder, TKey>
     where TBuilder : ResiliencePipelineBuilderBase
     where TKey : notnull
 {
@@ -75,7 +75,7 @@ private Builder CreateBuilder()
             builder);
     }
 
-    private record Builder(
+    private sealed record Builder(
         Func<PipelineComponent> ComponentFactory,
         List<CancellationToken> ReloadTokens,
         ResilienceStrategyTelemetry Telemetry,
diff --git a/src/Polly.Core/Simmy/Fault/ChaosFaultStrategy.cs b/src/Polly.Core/Simmy/Fault/ChaosFaultStrategy.cs
index 51b3a9e2914..6caede5ead6 100644
--- a/src/Polly.Core/Simmy/Fault/ChaosFaultStrategy.cs
+++ b/src/Polly.Core/Simmy/Fault/ChaosFaultStrategy.cs
@@ -2,7 +2,7 @@
 
 namespace Polly.Simmy.Fault;
 
-internal class ChaosFaultStrategy : ChaosStrategy
+internal sealed class ChaosFaultStrategy : ChaosStrategy
 {
     private readonly ResilienceStrategyTelemetry _telemetry;
 
diff --git a/src/Polly.Core/Simmy/Outcomes/ChaosOutcomeStrategy.cs b/src/Polly.Core/Simmy/Outcomes/ChaosOutcomeStrategy.cs
index e9f224bfb0b..b62cf94cbb9 100644
--- a/src/Polly.Core/Simmy/Outcomes/ChaosOutcomeStrategy.cs
+++ b/src/Polly.Core/Simmy/Outcomes/ChaosOutcomeStrategy.cs
@@ -2,7 +2,7 @@
 
 namespace Polly.Simmy.Outcomes;
 
-internal class ChaosOutcomeStrategy<T> : ChaosStrategy<T>
+internal sealed class ChaosOutcomeStrategy<T> : ChaosStrategy<T>
 {
     private readonly ResilienceStrategyTelemetry _telemetry;
     private readonly Func<OnOutcomeInjectedArguments<T>, ValueTask>? _onOutcomeInjected;
diff --git a/src/Polly.Core/Utils/Pipeline/ComponentWithDisposeCallbacks.cs b/src/Polly.Core/Utils/Pipeline/ComponentWithDisposeCallbacks.cs
index 61162a94528..ca407426ad2 100644
--- a/src/Polly.Core/Utils/Pipeline/ComponentWithDisposeCallbacks.cs
+++ b/src/Polly.Core/Utils/Pipeline/ComponentWithDisposeCallbacks.cs
@@ -1,6 +1,6 @@
 namespace Polly.Utils.Pipeline;
 
-internal class ComponentWithDisposeCallbacks : PipelineComponent
+internal sealed class ComponentWithDisposeCallbacks : PipelineComponent
 {
     private readonly List<Action> _callbacks;
 
diff --git a/src/Polly.Core/Utils/Pipeline/ExternalComponent.cs b/src/Polly.Core/Utils/Pipeline/ExternalComponent.cs
index e8ad4cd5583..de12647c0b0 100644
--- a/src/Polly.Core/Utils/Pipeline/ExternalComponent.cs
+++ b/src/Polly.Core/Utils/Pipeline/ExternalComponent.cs
@@ -1,7 +1,7 @@
 namespace Polly.Utils.Pipeline;
 
 [DebuggerDisplay("{Component}")]
-internal class ExternalComponent : PipelineComponent
+internal sealed class ExternalComponent : PipelineComponent
 {
     public ExternalComponent(PipelineComponent component) => Component = component;
 
diff --git a/src/Polly.Core/Utils/Pipeline/ReloadableComponent.cs b/src/Polly.Core/Utils/Pipeline/ReloadableComponent.cs
index 7e0b0435c1b..91c438ce2e7 100644
--- a/src/Polly.Core/Utils/Pipeline/ReloadableComponent.cs
+++ b/src/Polly.Core/Utils/Pipeline/ReloadableComponent.cs
@@ -98,15 +98,15 @@ private void DisposeRegistration()
         _tokenSource.Dispose();
     }
 
-    internal record ReloadFailedArguments(Exception Exception);
+    internal sealed record ReloadFailedArguments(Exception Exception);
 
-    internal record DisposedFailedArguments(Exception Exception);
+    internal sealed record DisposedFailedArguments(Exception Exception);
 
 #pragma warning disable S2094 // Classes should not be empty
 #pragma warning disable S3253 // Constructor and destructor declarations should not be redundant
-    internal record OnReloadArguments();
+    internal sealed record OnReloadArguments();
 #pragma warning restore S3253 // Constructor and destructor declarations should not be redundant
 #pragma warning restore S2094 // Classes should not be empty
 
-    internal record Entry(PipelineComponent Component, List<CancellationToken> ReloadTokens, ResilienceStrategyTelemetry Telemetry);
+    internal sealed record Entry(PipelineComponent Component, List<CancellationToken> ReloadTokens, ResilienceStrategyTelemetry Telemetry);
 }
diff --git a/src/Polly.Extensions/DependencyInjection/PollyServiceCollectionExtensions.cs b/src/Polly.Extensions/DependencyInjection/PollyServiceCollectionExtensions.cs
index 5b19cae5ef0..c310f22976e 100644
--- a/src/Polly.Extensions/DependencyInjection/PollyServiceCollectionExtensions.cs
+++ b/src/Polly.Extensions/DependencyInjection/PollyServiceCollectionExtensions.cs
@@ -288,7 +288,7 @@ private static void AddResiliencePipelineBuilder(this IServiceCollection service
         });
     }
 
-    private class RegistryMarker<TKey>
+    private sealed class RegistryMarker<TKey>
     {
         public static readonly ServiceDescriptor ServiceDescriptor = ServiceDescriptor.Singleton(new RegistryMarker<TKey>());
     }
diff --git a/src/Polly.Extensions/Telemetry/ResilienceTelemetryTags.cs b/src/Polly.Extensions/Telemetry/ResilienceTelemetryTags.cs
index 0f8ed179ecf..2a38a5b9b9f 100644
--- a/src/Polly.Extensions/Telemetry/ResilienceTelemetryTags.cs
+++ b/src/Polly.Extensions/Telemetry/ResilienceTelemetryTags.cs
@@ -1,6 +1,6 @@
 namespace Polly.Telemetry;
 
-internal class ResilienceTelemetryTags
+internal static class ResilienceTelemetryTags
 {
     public const string EventName = "event.name";
 
diff --git a/src/Polly/Caching/AsyncGenericCacheProvider.cs b/src/Polly/Caching/AsyncGenericCacheProvider.cs
index f7480745c81..090b8cb575a 100644
--- a/src/Polly/Caching/AsyncGenericCacheProvider.cs
+++ b/src/Polly/Caching/AsyncGenericCacheProvider.cs
@@ -5,7 +5,7 @@ namespace Polly.Caching;
 /// Provides a strongly-typed wrapper over a non-generic CacheProviderAsync.
 /// </summary>
 /// <typeparam name="TCacheFormat">The type of the objects in the cache.</typeparam>
-internal class AsyncGenericCacheProvider<TCacheFormat> : IAsyncCacheProvider<TCacheFormat>
+internal sealed class AsyncGenericCacheProvider<TCacheFormat> : IAsyncCacheProvider<TCacheFormat>
 {
     private readonly IAsyncCacheProvider _wrappedCacheProvider;
 
diff --git a/src/Polly/Caching/GenericCacheProvider.cs b/src/Polly/Caching/GenericCacheProvider.cs
index 73b617b667f..abfec5768be 100644
--- a/src/Polly/Caching/GenericCacheProvider.cs
+++ b/src/Polly/Caching/GenericCacheProvider.cs
@@ -5,7 +5,7 @@ namespace Polly.Caching;
 /// Provides a strongly-typed wrapper over a non-generic CacheProvider.
 /// </summary>
 /// <typeparam name="TCacheFormat">The type of the objects in the cache.</typeparam>
-internal class GenericCacheProvider<TCacheFormat> : ISyncCacheProvider<TCacheFormat>
+internal sealed class GenericCacheProvider<TCacheFormat> : ISyncCacheProvider<TCacheFormat>
 {
     private readonly ISyncCacheProvider _wrappedCacheProvider;
 
diff --git a/src/Polly/Caching/GenericTtlStrategy.cs b/src/Polly/Caching/GenericTtlStrategy.cs
index ec4a6dafea4..db22a8af750 100644
--- a/src/Polly/Caching/GenericTtlStrategy.cs
+++ b/src/Polly/Caching/GenericTtlStrategy.cs
@@ -4,7 +4,7 @@ namespace Polly.Caching;
 /// <summary>
 /// Represents a strongly-typed <see cref="ITtlStrategy"/> wrapper of a non-generic strategy.
 /// </summary>
-internal class GenericTtlStrategy<TResult> : ITtlStrategy<TResult>
+internal sealed class GenericTtlStrategy<TResult> : ITtlStrategy<TResult>
 {
     private readonly ITtlStrategy _wrappedTtlStrategy;
 
diff --git a/src/Polly/CircuitBreaker/AdvancedCircuitController.cs b/src/Polly/CircuitBreaker/AdvancedCircuitController.cs
index 15e69154599..79e4783007c 100644
--- a/src/Polly/CircuitBreaker/AdvancedCircuitController.cs
+++ b/src/Polly/CircuitBreaker/AdvancedCircuitController.cs
@@ -1,6 +1,6 @@
 namespace Polly.CircuitBreaker;
 
-internal class AdvancedCircuitController<TResult> : CircuitStateController<TResult>
+internal sealed class AdvancedCircuitController<TResult> : CircuitStateController<TResult>
 {
     private const short NumberOfWindows = 10;
     internal static readonly long ResolutionOfCircuitTimer = TimeSpan.FromMilliseconds(20).Ticks;
diff --git a/src/Polly/CircuitBreaker/AsyncCircuitBreakerEngine.cs b/src/Polly/CircuitBreaker/AsyncCircuitBreakerEngine.cs
index 89c6c31242c..1a5905fa228 100644
--- a/src/Polly/CircuitBreaker/AsyncCircuitBreakerEngine.cs
+++ b/src/Polly/CircuitBreaker/AsyncCircuitBreakerEngine.cs
@@ -1,6 +1,6 @@
 namespace Polly.CircuitBreaker;
 
-internal class AsyncCircuitBreakerEngine
+internal static class AsyncCircuitBreakerEngine
 {
     internal static async Task<TResult> ImplementationAsync<TResult>(
         Func<Context, CancellationToken, Task<TResult>> action,
diff --git a/src/Polly/CircuitBreaker/CircuitBreakerEngine.cs b/src/Polly/CircuitBreaker/CircuitBreakerEngine.cs
index a51fd4b8803..ef8883aac28 100644
--- a/src/Polly/CircuitBreaker/CircuitBreakerEngine.cs
+++ b/src/Polly/CircuitBreaker/CircuitBreakerEngine.cs
@@ -2,7 +2,7 @@
 
 namespace Polly.CircuitBreaker;
 
-internal class CircuitBreakerEngine
+internal static class CircuitBreakerEngine
 {
     internal static TResult Implementation<TResult>(
         Func<Context, CancellationToken, TResult> action,
diff --git a/src/Polly/CircuitBreaker/ConsecutiveCountCircuitController.cs b/src/Polly/CircuitBreaker/ConsecutiveCountCircuitController.cs
index a498c208f91..7f362d87d3d 100644
--- a/src/Polly/CircuitBreaker/ConsecutiveCountCircuitController.cs
+++ b/src/Polly/CircuitBreaker/ConsecutiveCountCircuitController.cs
@@ -1,6 +1,6 @@
 namespace Polly.CircuitBreaker;
 
-internal class ConsecutiveCountCircuitController<TResult> : CircuitStateController<TResult>
+internal sealed class ConsecutiveCountCircuitController<TResult> : CircuitStateController<TResult>
 {
     private readonly int _exceptionsAllowedBeforeBreaking;
     private int _consecutiveFailureCount;
diff --git a/src/Polly/CircuitBreaker/HealthCount.cs b/src/Polly/CircuitBreaker/HealthCount.cs
index 92a6fd8e286..d9d16fa78af 100644
--- a/src/Polly/CircuitBreaker/HealthCount.cs
+++ b/src/Polly/CircuitBreaker/HealthCount.cs
@@ -1,6 +1,6 @@
 namespace Polly.CircuitBreaker;
 
-internal class HealthCount
+internal sealed class HealthCount
 {
     public int Successes { get; set; }
 
diff --git a/src/Polly/CircuitBreaker/RollingHealthMetrics.cs b/src/Polly/CircuitBreaker/RollingHealthMetrics.cs
index 167da0065f4..23c1d7465b3 100644
--- a/src/Polly/CircuitBreaker/RollingHealthMetrics.cs
+++ b/src/Polly/CircuitBreaker/RollingHealthMetrics.cs
@@ -1,7 +1,7 @@
 #nullable enable
 namespace Polly.CircuitBreaker;
 
-internal class RollingHealthMetrics : IHealthMetrics
+internal sealed class RollingHealthMetrics : IHealthMetrics
 {
     private readonly long _samplingDuration;
     private readonly long _windowDuration;
diff --git a/src/Polly/CircuitBreaker/SingleHealthMetrics.cs b/src/Polly/CircuitBreaker/SingleHealthMetrics.cs
index e17859f6a67..3e6e6568b50 100644
--- a/src/Polly/CircuitBreaker/SingleHealthMetrics.cs
+++ b/src/Polly/CircuitBreaker/SingleHealthMetrics.cs
@@ -1,7 +1,7 @@
 #nullable enable
 namespace Polly.CircuitBreaker;
 
-internal class SingleHealthMetrics : IHealthMetrics
+internal sealed class SingleHealthMetrics : IHealthMetrics
 {
     private readonly long _samplingDuration;
 
diff --git a/src/Polly/Fallback/AsyncFallbackEngine.cs b/src/Polly/Fallback/AsyncFallbackEngine.cs
index b0e9e48c740..79a58554b32 100644
--- a/src/Polly/Fallback/AsyncFallbackEngine.cs
+++ b/src/Polly/Fallback/AsyncFallbackEngine.cs
@@ -1,7 +1,7 @@
 #nullable enable
 namespace Polly.Fallback;
 
-internal class AsyncFallbackEngine
+internal static class AsyncFallbackEngine
 {
     internal static async Task<TResult> ImplementationAsync<TResult>(
         Func<Context, CancellationToken, Task<TResult>> action,
diff --git a/src/Polly/Utilities/TimedLock.cs b/src/Polly/Utilities/TimedLock.cs
index da5055fd2d1..582c99c5abf 100644
--- a/src/Polly/Utilities/TimedLock.cs
+++ b/src/Polly/Utilities/TimedLock.cs
@@ -68,7 +68,7 @@ public void Dispose()
 #if DEBUG
     // (In Debug mode, we make it a class so that we can add a finalizer
     // in order to detect when the object is not freed.)
-    private class Sentinel
+    private sealed class Sentinel
     {
 #if NETSTANDARD2_0
         ~Sentinel()
@@ -85,7 +85,7 @@ private class Sentinel
 #endif
 }
 
-internal class LockTimeoutException : Exception
+internal sealed class LockTimeoutException : Exception
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="LockTimeoutException"/> class.