diff --git a/Security/src/AuthApi/LocalMutualTlsSupport.cs b/Security/src/AuthApi/LocalMutualTlsSupport.cs
new file mode 100644
index 00000000..7280b687
--- /dev/null
+++ b/Security/src/AuthApi/LocalMutualTlsSupport.cs
@@ -0,0 +1,94 @@
+using System.Net;
+using System.Net.Security;
+using System.Security.Cryptography.X509Certificates;
+using Microsoft.AspNetCore.Server.Kestrel.Core;
+using Microsoft.AspNetCore.Server.Kestrel.Https;
+
+namespace Steeltoe.Samples.AuthApi;
+
+internal static class LocalMutualTlsSupport
+{
+    private const string ForwardedClientCertHeaderName = "X-Forwarded-Client-Cert";
+
+    // Mirrors LocalCertificateWriter's layout in Steeltoe.Common.Certificates: CA materials live one level
+    // up from the app directory, under GeneratedCertificates/trust, shared across samples in the solution.
+    private static readonly string TrustStorePath = ResolveTrustStorePath();
+    private static readonly X509Certificate2 RootCaCertificate = LoadTrustedCertificate("SteeltoeCA.crt");
+    private static readonly X509Certificate2 IntermediateCertificate = LoadTrustedCertificate("SteeltoeIntermediate.crt");
+
+    public static IServiceCollection AddLocalMutualTlsSupport(this IServiceCollection services)
+    {
+        services.PostConfigure<KestrelServerOptions>(options => options.ConfigureHttpsDefaults(httpsOptions =>
+        {
+            httpsOptions.ClientCertificateMode = ClientCertificateMode.AllowCertificate;
+
+            // Kestrel's default validation rejects Steeltoe certs because the Steeltoe-generated CA isn't OS-trusted.
+            // Validate against the Steeltoe CA/intermediate chain directly instead of trusting the OS store.
+            httpsOptions.ClientCertificateValidation = ValidateAgainstSteeltoeTrustChain;
+        }));
+
+        return services;
+    }
+
+    public static IApplicationBuilder UseLocalMutualTlsSupport(this IApplicationBuilder builder)
+    {
+        builder.Use(async (context, next) =>
+        {
+            context.Request.Headers.Remove(ForwardedClientCertHeaderName);
+
+            if (IsLoopbackAddress(context.Connection.RemoteIpAddress) && context.Connection.ClientCertificate != null)
+            {
+                context.Request.Headers[ForwardedClientCertHeaderName] = Convert.ToBase64String(context.Connection.ClientCertificate.RawData);
+            }
+
+            await next(context);
+        });
+
+        return builder;
+    }
+
+    private static bool IsLoopbackAddress(IPAddress? address)
+    {
+        if (address == null)
+        {
+            return false;
+        }
+
+        if (address.IsIPv4MappedToIPv6)
+        {
+            address = address.MapToIPv4();
+        }
+
+        return IPAddress.IsLoopback(address);
+    }
+
+    private static bool ValidateAgainstSteeltoeTrustChain(X509Certificate2? certificate, X509Chain? remoteChain, SslPolicyErrors sslPolicyErrors)
+    {
+        if (certificate == null)
+        {
+            return false;
+        }
+
+        using var customChain = new X509Chain();
+        customChain.ChainPolicy.TrustMode = X509ChainTrustMode.CustomRootTrust;
+        customChain.ChainPolicy.CustomTrustStore.Add(RootCaCertificate);
+        customChain.ChainPolicy.RevocationMode = X509RevocationMode.NoCheck;
+
+        return customChain.Build(certificate);
+    }
+
+    private static string ResolveTrustStorePath()
+    {
+        string appBasePath = AppContext.BaseDirectory.Contains($"{Path.DirectorySeparatorChar}bin{Path.DirectorySeparatorChar}", StringComparison.Ordinal)
+            ? AppContext.BaseDirectory[..AppContext.BaseDirectory.LastIndexOf($"{Path.DirectorySeparatorChar}bin", StringComparison.Ordinal)]
+            : AppContext.BaseDirectory[..^1];
+
+        string parentPath = Directory.GetParent(appBasePath)?.ToString() ?? string.Empty;
+        return Path.Combine(parentPath, "GeneratedCertificates", "trust");
+    }
+
+    private static X509Certificate2 LoadTrustedCertificate(string fileName)
+    {
+        return X509Certificate2.CreateFromPem(File.ReadAllText(Path.Combine(TrustStorePath, fileName)));
+    }
+}
diff --git a/Security/src/AuthApi/Program.cs b/Security/src/AuthApi/Program.cs
index bef41923..2930fbb7 100644
--- a/Security/src/AuthApi/Program.cs
+++ b/Security/src/AuthApi/Program.cs
@@ -24,6 +24,12 @@
 // Steeltoe: Add instance identity certificate to configuration.
 builder.Configuration.AddAppInstanceIdentityCertificate(new Guid(orgId), new Guid(spaceId));
 
+if (builder.Environment.IsDevelopment())
+{
+    // Steeltoe: Simulate Gorouter's mTLS termination locally.
+    builder.Services.AddLocalMutualTlsSupport();
+}
+
 // Steeltoe: Register Microsoft's JWT Bearer and Certificate libraries for authentication, configure JWT to work with UAA/Cloud Foundry.
 builder.Services.AddAuthentication().AddJwtBearer().ConfigureJwtBearerForCloudFoundry().AddCertificate();
 
@@ -35,13 +41,19 @@
         policy.RequireClaim("scope", Globals.RequiredJwtScope);
     })
     // Steeltoe: Register policies requiring space or org to match between client and server certificates.
-    .AddOrgAndSpacePolicies();
+    .AddOrgAndSpacePoliciesForMutualTls();
 
 // Steeltoe: Add actuator endpoints.
 builder.Services.AddAllActuators();
 
 WebApplication app = builder.Build();
 
+if (app.Environment.IsDevelopment())
+{
+    // Steeltoe: Simulate Gorouter's mTLS termination locally.
+    app.UseLocalMutualTlsSupport();
+}
+
 // Steeltoe: Use certificate and header forwarding along with ASP.NET Core Authentication and Authorization middleware.
 app.UseCertificateAuthorization();
 
diff --git a/Security/src/AuthConsole/Program.cs b/Security/src/AuthConsole/Program.cs
index 209fbc88..e7d875e8 100644
--- a/Security/src/AuthConsole/Program.cs
+++ b/Security/src/AuthConsole/Program.cs
@@ -20,7 +20,7 @@
 builder.Configuration.AddAppInstanceIdentityCertificate(new Guid(orgId), new Guid(spaceId));
 
 // Steeltoe: register a typed HttpClient that includes the application instance identity certificate.
-builder.Services.AddHttpClient<CertificateAuthorizationApiClient>(SetBaseAddress).AddAppInstanceIdentityCertificate().ConfigureLogging();
+builder.Services.AddHttpClient<CertificateAuthorizationApiClient>(SetBaseAddress).AddAppInstanceIdentityCertificateForMutualTls().ConfigureLogging();
 
 IHost host = builder.Build();
 host.Run();
diff --git a/Security/src/AuthWeb/Program.cs b/Security/src/AuthWeb/Program.cs
index 0c0a9b14..49bf577e 100644
--- a/Security/src/AuthWeb/Program.cs
+++ b/Security/src/AuthWeb/Program.cs
@@ -42,7 +42,7 @@
 
 // Steeltoe: Register HttpClients for communicating with a backend service, including an application instance certificate for authorization.
 builder.Services.AddHttpClient<JwtAuthorizationApiClient>(SetBaseAddress).ConfigureLogging();
-builder.Services.AddHttpClient<CertificateAuthorizationApiClient>(SetBaseAddress).AddAppInstanceIdentityCertificate().ConfigureLogging();
+builder.Services.AddHttpClient<CertificateAuthorizationApiClient>(SetBaseAddress).AddAppInstanceIdentityCertificateForMutualTls().ConfigureLogging();
 
 // Steeltoe: Add actuator endpoints.
 builder.Services.AddAllActuators();