diff --git a/codegen/smithy-aws-go-codegen/src/main/resources/software/amazon/smithy/aws/go/codegen/endpoints.json b/codegen/smithy-aws-go-codegen/src/main/resources/software/amazon/smithy/aws/go/codegen/endpoints.json
index 4c4ab691241..a2628f52cca 100644
--- a/codegen/smithy-aws-go-codegen/src/main/resources/software/amazon/smithy/aws/go/codegen/endpoints.json
+++ b/codegen/smithy-aws-go-codegen/src/main/resources/software/amazon/smithy/aws/go/codegen/endpoints.json
@@ -1224,26 +1224,126 @@
       },
       "appmesh" : {
         "endpoints" : {
-          "af-south-1" : { },
-          "ap-east-1" : { },
-          "ap-northeast-1" : { },
-          "ap-northeast-2" : { },
-          "ap-south-1" : { },
-          "ap-southeast-1" : { },
-          "ap-southeast-2" : { },
-          "ca-central-1" : { },
-          "eu-central-1" : { },
-          "eu-north-1" : { },
-          "eu-south-1" : { },
-          "eu-west-1" : { },
-          "eu-west-2" : { },
-          "eu-west-3" : { },
-          "me-south-1" : { },
-          "sa-east-1" : { },
-          "us-east-1" : { },
-          "us-east-2" : { },
-          "us-west-1" : { },
-          "us-west-2" : { }
+          "af-south-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.af-south-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ap-east-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ap-east-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ap-northeast-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ap-northeast-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ap-northeast-2" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ap-northeast-2.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ap-south-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ap-south-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ap-southeast-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ap-southeast-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ap-southeast-2" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ap-southeast-2.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "ca-central-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.ca-central-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "eu-central-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.eu-central-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "eu-north-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.eu-north-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "eu-south-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.eu-south-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "eu-west-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.eu-west-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "eu-west-2" : {
+            "variants" : [ {
+              "hostname" : "appmesh.eu-west-2.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "eu-west-3" : {
+            "variants" : [ {
+              "hostname" : "appmesh.eu-west-3.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "me-south-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.me-south-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "sa-east-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.sa-east-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "us-east-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.us-east-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "us-east-2" : {
+            "variants" : [ {
+              "hostname" : "appmesh.us-east-2.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "us-west-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.us-west-1.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "us-west-2" : {
+            "variants" : [ {
+              "hostname" : "appmesh.us-west-2.api.aws",
+              "tags" : [ "dualstack" ]
+            } ]
+          }
         }
       },
       "apprunner" : {
@@ -12129,12 +12229,60 @@
           "eu-west-1" : { },
           "eu-west-2" : { },
           "eu-west-3" : { },
+          "fips-us-east-1" : {
+            "credentialScope" : {
+              "region" : "us-east-1"
+            },
+            "deprecated" : true,
+            "hostname" : "synthetics-fips.us-east-1.amazonaws.com"
+          },
+          "fips-us-east-2" : {
+            "credentialScope" : {
+              "region" : "us-east-2"
+            },
+            "deprecated" : true,
+            "hostname" : "synthetics-fips.us-east-2.amazonaws.com"
+          },
+          "fips-us-west-1" : {
+            "credentialScope" : {
+              "region" : "us-west-1"
+            },
+            "deprecated" : true,
+            "hostname" : "synthetics-fips.us-west-1.amazonaws.com"
+          },
+          "fips-us-west-2" : {
+            "credentialScope" : {
+              "region" : "us-west-2"
+            },
+            "deprecated" : true,
+            "hostname" : "synthetics-fips.us-west-2.amazonaws.com"
+          },
           "me-south-1" : { },
           "sa-east-1" : { },
-          "us-east-1" : { },
-          "us-east-2" : { },
-          "us-west-1" : { },
-          "us-west-2" : { }
+          "us-east-1" : {
+            "variants" : [ {
+              "hostname" : "synthetics-fips.us-east-1.amazonaws.com",
+              "tags" : [ "fips" ]
+            } ]
+          },
+          "us-east-2" : {
+            "variants" : [ {
+              "hostname" : "synthetics-fips.us-east-2.amazonaws.com",
+              "tags" : [ "fips" ]
+            } ]
+          },
+          "us-west-1" : {
+            "variants" : [ {
+              "hostname" : "synthetics-fips.us-west-1.amazonaws.com",
+              "tags" : [ "fips" ]
+            } ]
+          },
+          "us-west-2" : {
+            "variants" : [ {
+              "hostname" : "synthetics-fips.us-west-2.amazonaws.com",
+              "tags" : [ "fips" ]
+            } ]
+          }
         }
       },
       "tagging" : {
@@ -13258,8 +13406,18 @@
       },
       "appmesh" : {
         "endpoints" : {
-          "cn-north-1" : { },
-          "cn-northwest-1" : { }
+          "cn-north-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.cn-north-1.api.amazonwebservices.com.cn",
+              "tags" : [ "dualstack" ]
+            } ]
+          },
+          "cn-northwest-1" : {
+            "variants" : [ {
+              "hostname" : "appmesh.cn-northwest-1.api.amazonwebservices.com.cn",
+              "tags" : [ "dualstack" ]
+            } ]
+          }
         }
       },
       "appsync" : {
@@ -17539,8 +17697,32 @@
       },
       "synthetics" : {
         "endpoints" : {
-          "us-gov-east-1" : { },
-          "us-gov-west-1" : { }
+          "fips-us-gov-east-1" : {
+            "credentialScope" : {
+              "region" : "us-gov-east-1"
+            },
+            "deprecated" : true,
+            "hostname" : "synthetics-fips.us-gov-east-1.amazonaws.com"
+          },
+          "fips-us-gov-west-1" : {
+            "credentialScope" : {
+              "region" : "us-gov-west-1"
+            },
+            "deprecated" : true,
+            "hostname" : "synthetics-fips.us-gov-west-1.amazonaws.com"
+          },
+          "us-gov-east-1" : {
+            "variants" : [ {
+              "hostname" : "synthetics-fips.us-gov-east-1.amazonaws.com",
+              "tags" : [ "fips" ]
+            } ]
+          },
+          "us-gov-west-1" : {
+            "variants" : [ {
+              "hostname" : "synthetics-fips.us-gov-west-1.amazonaws.com",
+              "tags" : [ "fips" ]
+            } ]
+          }
         }
       },
       "tagging" : {