diff --git a/AUTHORS b/AUTHORS
index 7d26d11e1d4c..fe82a109bdfc 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -26,3 +26,4 @@ Sarthak Verma <sarthak@artiosys.com>
 Mike Diarmid <mike@invertase.io>
 Invertase <oss@invertase.io>
 Elliot Hesp <elliot@invertase.io>
+Twin Sun, LLC <google-contrib@twinsunsolutions.com>
diff --git a/packages/google_sign_in/android/src/main/java/io/flutter/plugins/googlesignin/GoogleSignInPlugin.java b/packages/google_sign_in/android/src/main/java/io/flutter/plugins/googlesignin/GoogleSignInPlugin.java
index d2fc260c7b1c..879ebbfc1dbf 100755
--- a/packages/google_sign_in/android/src/main/java/io/flutter/plugins/googlesignin/GoogleSignInPlugin.java
+++ b/packages/google_sign_in/android/src/main/java/io/flutter/plugins/googlesignin/GoogleSignInPlugin.java
@@ -66,7 +66,8 @@ public void onMethodCall(MethodCall call, Result result) {
         String signInOption = call.argument("signInOption");
         List<String> requestedScopes = call.argument("scopes");
         String hostedDomain = call.argument("hostedDomain");
-        delegate.init(result, signInOption, requestedScopes, hostedDomain);
+        String serverClientId = call.argument("serverClientId");
+        delegate.init(result, signInOption, requestedScopes, hostedDomain, serverClientId);
         break;
 
       case METHOD_SIGN_IN_SILENTLY:
@@ -113,7 +114,11 @@ public void onMethodCall(MethodCall call, Result result) {
   public interface IDelegate {
     /** Initializes this delegate so that it is ready to perform other operations. */
     public void init(
-        Result result, String signInOption, List<String> requestedScopes, String hostedDomain);
+        Result result,
+        String signInOption,
+        List<String> requestedScopes,
+        String hostedDomain,
+        String serverClientId);
 
     /**
      * Returns the account information for the user who is signed in to this app. If no user is
@@ -210,7 +215,11 @@ private void checkAndSetPendingOperation(String method, Result result, Object da
      */
     @Override
     public void init(
-        Result result, String signInOption, List<String> requestedScopes, String hostedDomain) {
+        Result result,
+        String signInOption,
+        List<String> requestedScopes,
+        String hostedDomain,
+        String serverClientId) {
       try {
         GoogleSignInOptions.Builder optionsBuilder;
 
@@ -246,6 +255,10 @@ public void init(
         if (!Strings.isNullOrEmpty(hostedDomain)) {
           optionsBuilder.setHostedDomain(hostedDomain);
         }
+        if (!Strings.isNullOrEmpty(serverClientId)) {
+          optionsBuilder.requestServerAuthCode(serverClientId, true);
+          optionsBuilder.requestIdToken(serverClientId);
+        }
 
         this.requestedScopes = requestedScopes;
         signInClient = GoogleSignIn.getClient(registrar.context(), optionsBuilder.build());
@@ -361,6 +374,7 @@ private void onSignInAccount(GoogleSignInAccount account) {
       response.put("id", account.getId());
       response.put("idToken", account.getIdToken());
       response.put("displayName", account.getDisplayName());
+      response.put("serverAuthCode", account.getServerAuthCode());
       if (account.getPhotoUrl() != null) {
         response.put("photoUrl", account.getPhotoUrl().toString());
       }
diff --git a/packages/google_sign_in/ios/Classes/GoogleSignInPlugin.m b/packages/google_sign_in/ios/Classes/GoogleSignInPlugin.m
index 483bc5c6e81c..bfae40d25ec4 100644
--- a/packages/google_sign_in/ios/Classes/GoogleSignInPlugin.m
+++ b/packages/google_sign_in/ios/Classes/GoogleSignInPlugin.m
@@ -75,6 +75,9 @@ - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result
         [GIDSignIn sharedInstance].clientID = plist[kClientIdKey];
         [GIDSignIn sharedInstance].scopes = call.arguments[@"scopes"];
         [GIDSignIn sharedInstance].hostedDomain = call.arguments[@"hostedDomain"];
+        if (![call.arguments[@"serverClientId"] isEqual:[NSNull null]]) {
+          [GIDSignIn sharedInstance].serverClientID = call.arguments[@"serverClientId"];
+        }
         result(nil);
       } else {
         result([FlutterError errorWithCode:@"missing-config"
@@ -173,6 +176,7 @@ - (void)signIn:(GIDSignIn *)signIn
       @"email" : user.profile.email ?: [NSNull null],
       @"id" : user.userID ?: [NSNull null],
       @"photoUrl" : [photoUrl absoluteString] ?: [NSNull null],
+      @"serverAuthCode" : user.serverAuthCode ?: [NSNull null]
     }
                        error:nil];
   }
diff --git a/packages/google_sign_in/lib/google_sign_in.dart b/packages/google_sign_in/lib/google_sign_in.dart
index 234eb5102da2..b1257bd4a2b1 100755
--- a/packages/google_sign_in/lib/google_sign_in.dart
+++ b/packages/google_sign_in/lib/google_sign_in.dart
@@ -36,7 +36,8 @@ class GoogleSignInAccount implements GoogleIdentity {
         email = data['email'],
         id = data['id'],
         photoUrl = data['photoUrl'],
-        _idToken = data['idToken'] {
+        _idToken = data['idToken'],
+        serverAuthCode = data['serverAuthCode'] {
     assert(id != null);
   }
 
@@ -62,6 +63,7 @@ class GoogleSignInAccount implements GoogleIdentity {
 
   final String _idToken;
   final GoogleSignIn _googleSignIn;
+  final String serverAuthCode;
 
   /// Retrieve [GoogleSignInAuthentication] for this account.
   ///
@@ -163,14 +165,17 @@ class GoogleSignIn {
   /// The [hostedDomain] argument specifies a hosted domain restriction. By
   /// setting this, sign in will be restricted to accounts of the user in the
   /// specified domain. By default, the list of accounts will not be restricted.
-  GoogleSignIn({this.signInOption, this.scopes, this.hostedDomain});
+  GoogleSignIn(
+      {this.signInOption, this.scopes, this.hostedDomain, this.serverClientId});
 
   /// Factory for creating default sign in user experience.
-  factory GoogleSignIn.standard({List<String> scopes, String hostedDomain}) {
+  factory GoogleSignIn.standard(
+      {List<String> scopes, String hostedDomain, String serverClientId}) {
     return GoogleSignIn(
         signInOption: SignInOption.standard,
         scopes: scopes,
-        hostedDomain: hostedDomain);
+        hostedDomain: hostedDomain,
+        serverClientId: serverClientId);
   }
 
   /// Factory for creating sign in suitable for games. This option must not be
@@ -207,6 +212,8 @@ class GoogleSignIn {
   /// Domain to restrict sign-in to.
   final String hostedDomain;
 
+  final String serverClientId;
+
   StreamController<GoogleSignInAccount> _currentUserController =
       StreamController<GoogleSignInAccount>.broadcast();
 
@@ -246,6 +253,7 @@ class GoogleSignIn {
         'signInOption': (signInOption ?? SignInOption.standard).toString(),
         'scopes': scopes ?? <String>[],
         'hostedDomain': hostedDomain,
+        'serverClientId': serverClientId,
       })
         ..catchError((dynamic _) {
           // Invalidate initialization if it errored out.
diff --git a/packages/google_sign_in/test/google_sign_in_test.dart b/packages/google_sign_in/test/google_sign_in_test.dart
index b0ba5e82d3e2..c3951a88f12c 100755
--- a/packages/google_sign_in/test/google_sign_in_test.dart
+++ b/packages/google_sign_in/test/google_sign_in_test.dart
@@ -59,6 +59,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
         ],
@@ -75,6 +76,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signIn', arguments: null),
         ],
@@ -89,6 +91,7 @@ void main() {
           'signInOption': 'SignInOption.standard',
           'scopes': <String>[],
           'hostedDomain': null,
+          'serverClientId': null,
         }),
         isMethodCall('signOut', arguments: null),
       ]);
@@ -104,6 +107,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('disconnect', arguments: null),
         ],
@@ -121,6 +125,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('disconnect', arguments: null),
         ],
@@ -135,6 +140,7 @@ void main() {
           'signInOption': 'SignInOption.standard',
           'scopes': <String>[],
           'hostedDomain': null,
+          'serverClientId': null,
         }),
         isMethodCall('isSignedIn', arguments: null),
       ]);
@@ -161,6 +167,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
         ],
@@ -178,6 +185,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
           isMethodCall('signIn', arguments: null),
@@ -200,6 +208,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
         ],
@@ -231,6 +240,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signOut', arguments: null),
           isMethodCall('signOut', arguments: null),
@@ -256,6 +266,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
           isMethodCall('signOut', arguments: null),
@@ -307,6 +318,7 @@ void main() {
             'signInOption': 'SignInOption.standard',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
         ],
@@ -326,6 +338,7 @@ void main() {
             'signInOption': 'SignInOption.games',
             'scopes': <String>[],
             'hostedDomain': null,
+            'serverClientId': null,
           }),
           isMethodCall('signInSilently', arguments: null),
         ],