diff --git a/src/Authress.SDK/Client/TokenVerifier.cs b/src/Authress.SDK/Client/TokenVerifier.cs
index f2445af..dbfc21d 100644
--- a/src/Authress.SDK/Client/TokenVerifier.cs
+++ b/src/Authress.SDK/Client/TokenVerifier.cs
@@ -156,9 +156,11 @@ public async Task<VerifiedUserIdentity> VerifyToken(string authorizationHeaderVa
                 throw new ArgumentNullException("The authress custom domain must be specified in the AuthressSettings.");
             }
 
-            var completeIssuerUrl = new Uri(Sanitizers.SanitizeUrl(authressCustomDomain));
+            var completeIssuerUrl = new Uri(Sanitizers.SanitizeIssuerUrl(authressCustomDomain));
+            var altIssuerUrl = new Uri(Sanitizers.SanitizeUrl(authressCustomDomain));
             try {
-                if (new Uri(unverifiedJwtPayload.Issuer).GetLeftPart(UriPartial.Authority) != completeIssuerUrl.GetLeftPart(UriPartial.Authority)) {
+                if (new Uri(unverifiedJwtPayload.Issuer).GetLeftPart(UriPartial.Authority) != completeIssuerUrl.GetLeftPart(UriPartial.Authority)
+                    && new Uri(unverifiedJwtPayload.Issuer).GetLeftPart(UriPartial.Authority) != altIssuerUrl.GetLeftPart(UriPartial.Authority)) {
                     throw new TokenVerificationException($"Unauthorized: Invalid Issuer: {unverifiedJwtPayload.Issuer}");
                 }
             } catch (Exception) {
diff --git a/src/Authress.SDK/Utilities/Sanitizers.cs b/src/Authress.SDK/Utilities/Sanitizers.cs
index b2de374..59fef33 100644
--- a/src/Authress.SDK/Utilities/Sanitizers.cs
+++ b/src/Authress.SDK/Utilities/Sanitizers.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Text.RegularExpressions;
 
 namespace Authress.SDK.Utilities {
@@ -18,5 +19,24 @@ internal static string SanitizeUrl(string urlString) {
 
             return $"https://{urlString}";
         }
+
+        internal static string SanitizeIssuerUrl(string rawUrlString) {
+            var sanitizedUrlString = rawUrlString;
+            if (!sanitizedUrlString.StartsWith("http")) {
+                sanitizedUrlString = Regex.IsMatch(sanitizedUrlString, @"^(localhost|authress.localhost.localstack.cloud:4566$)") ? $"http://{sanitizedUrlString}" : $"https://{sanitizedUrlString}";
+            }
+
+            var sanitizedUrl = new Uri(sanitizedUrlString);
+            var domainBaseUrlMatch = Regex.Match(sanitizedUrl.GetLeftPart(UriPartial.Authority), @"^https?://([a-z0-9-]+)[.][a-z0-9-]+[.]authress[.]io$");
+            if (domainBaseUrlMatch.Success) {
+                var newSanitizedUrl = new UriBuilder(sanitizedUrl)
+                {
+                    Host = $"{domainBaseUrlMatch.Groups[1].Value}.login.authress.io"
+                };
+                sanitizedUrlString = newSanitizedUrl.Uri.ToString();
+            }
+
+            return sanitizedUrlString.Replace(@"[/]+$", "");
+        }
     }
 }
diff --git a/tests/Authress.SDK/Client/Tokenverifier/VerifyTokenTests.cs b/tests/Authress.SDK/Client/Tokenverifier/VerifyTokenTests.cs
index a4d7e91..d11dd2f 100644
--- a/tests/Authress.SDK/Client/Tokenverifier/VerifyTokenTests.cs
+++ b/tests/Authress.SDK/Client/Tokenverifier/VerifyTokenTests.cs
@@ -58,6 +58,85 @@ public async Task ValidateEddsaToken() {
             mockHttpClient.VerifyAll();
         }
 
+        [Fact]
+        public async Task ValidateTokenWithAltCustomDomain() {
+            var testUserId = Guid.NewGuid().ToString();
+            var testKeyId = Guid.NewGuid().ToString();
+            var authressClientTokenProvider = new AuthressClientTokenProvider($"{testUserId}.{testKeyId}.account.{eddsaKeys.Item1}", "authress.login.authress.io");
+            // setup
+            var edDsaJwkResponse = new JwkResponse { Keys = new List<Jwk> { new Jwk { Alg = Alg.EdDSA, kid = testKeyId, x = eddsaKeys.Item2 } } };
+            var jwtToken = await authressClientTokenProvider.GetBearerToken();
+
+            var mockHttpClient = new Mock<HttpClientHandler>(MockBehavior.Strict);
+            mockHttpClient.Protected().SetupSequence<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .ReturnsAsync(() => new HttpResponseMessage { StatusCode = HttpStatusCode.OK, Content = edDsaJwkResponse.ToHttpContent() });
+
+            var mockFactory = new Mock<IHttpClientHandlerFactory>(MockBehavior.Strict);
+            mockFactory.Setup(factory => factory.Create()).Returns(mockHttpClient.Object);
+
+            var mockHttpClientProvider = new HttpClientProvider(null, null, mockFactory.Object);
+            var tokenVerifier = new SDK.TokenVerifier("authress.api-eu-west.authress.io", mockHttpClientProvider);
+
+            var result = await tokenVerifier.VerifyToken(jwtToken);
+            result.Should().BeEquivalentTo(new VerifiedUserIdentity { UserId = testUserId });
+
+            mockFactory.Verify(mockFactory => mockFactory.Create(), Times.Once());
+            mockHttpClient.VerifyAll();
+        }
+
+        [Fact]
+        public async Task ValidateTokenWithAltCustomDomainForBoth() {
+            var testUserId = Guid.NewGuid().ToString();
+            var testKeyId = Guid.NewGuid().ToString();
+            var authressClientTokenProvider = new AuthressClientTokenProvider($"{testUserId}.{testKeyId}.account.{eddsaKeys.Item1}", "authress.api-eu-west.authress.io");
+            // setup
+            var edDsaJwkResponse = new JwkResponse { Keys = new List<Jwk> { new Jwk { Alg = Alg.EdDSA, kid = testKeyId, x = eddsaKeys.Item2 } } };
+            var jwtToken = await authressClientTokenProvider.GetBearerToken();
+
+            var mockHttpClient = new Mock<HttpClientHandler>(MockBehavior.Strict);
+            mockHttpClient.Protected().SetupSequence<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .ReturnsAsync(() => new HttpResponseMessage { StatusCode = HttpStatusCode.OK, Content = edDsaJwkResponse.ToHttpContent() });
+
+            var mockFactory = new Mock<IHttpClientHandlerFactory>(MockBehavior.Strict);
+            mockFactory.Setup(factory => factory.Create()).Returns(mockHttpClient.Object);
+
+            var mockHttpClientProvider = new HttpClientProvider(null, null, mockFactory.Object);
+            var tokenVerifier = new SDK.TokenVerifier("authress.api-eu-west.authress.io", mockHttpClientProvider);
+
+            var result = await tokenVerifier.VerifyToken(jwtToken);
+            result.Should().BeEquivalentTo(new VerifiedUserIdentity { UserId = testUserId });
+
+            mockFactory.Verify(mockFactory => mockFactory.Create(), Times.Once());
+            mockHttpClient.VerifyAll();
+        }
+
+
+        [Fact]
+        public async Task ValidateTokenWithNoCustomDomain() {
+            var testUserId = Guid.NewGuid().ToString();
+            var testKeyId = Guid.NewGuid().ToString();
+            var authressClientTokenProvider = new AuthressClientTokenProvider($"{testUserId}.{testKeyId}.account.{eddsaKeys.Item1}", "authress.login.authress.io");
+            // setup
+            var edDsaJwkResponse = new JwkResponse { Keys = new List<Jwk> { new Jwk { Alg = Alg.EdDSA, kid = testKeyId, x = eddsaKeys.Item2 } } };
+            var jwtToken = await authressClientTokenProvider.GetBearerToken();
+
+            var mockHttpClient = new Mock<HttpClientHandler>(MockBehavior.Strict);
+            mockHttpClient.Protected().SetupSequence<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .ReturnsAsync(() => new HttpResponseMessage { StatusCode = HttpStatusCode.OK, Content = edDsaJwkResponse.ToHttpContent() });
+
+            var mockFactory = new Mock<IHttpClientHandlerFactory>(MockBehavior.Strict);
+            mockFactory.Setup(factory => factory.Create()).Returns(mockHttpClient.Object);
+
+            var mockHttpClientProvider = new HttpClientProvider(null, null, mockFactory.Object);
+            var tokenVerifier = new SDK.TokenVerifier("authress.login.authress.io", mockHttpClientProvider);
+
+            var result = await tokenVerifier.VerifyToken(jwtToken);
+            result.Should().BeEquivalentTo(new VerifiedUserIdentity { UserId = testUserId });
+
+            mockFactory.Verify(mockFactory => mockFactory.Create(), Times.Once());
+            mockHttpClient.VerifyAll();
+        }
+
         [Fact]
         public async Task ValidateEddsaTokenWithExtraSpaces() {
             var testUserId = Guid.NewGuid().ToString();