diff --git a/taiga/external_apps/api.py b/taiga/external_apps/api.py
index 931337a8..8ded55d5 100644
--- a/taiga/external_apps/api.py
+++ b/taiga/external_apps/api.py
@@ -17,6 +17,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from . import serializers
+from . import validators
 from . import models
 from . import permissions
 from . import services
@@ -27,12 +28,12 @@ from taiga.base.api import ModelCrudViewSet, ModelRetrieveViewSet
 from taiga.base.api.utils import get_object_or_404
 from taiga.base.decorators import list_route, detail_route
 
-from django.db import transaction
 from django.utils.translation import ugettext_lazy as _
 
 
 class Application(ModelRetrieveViewSet):
     serializer_class = serializers.ApplicationSerializer
+    validator_class = validators.ApplicationValidator
     permission_classes = (permissions.ApplicationPermission,)
     model = models.Application
 
@@ -61,6 +62,7 @@ class Application(ModelRetrieveViewSet):
 
 class ApplicationToken(ModelCrudViewSet):
     serializer_class = serializers.ApplicationTokenSerializer
+    validator_class = validators.ApplicationTokenValidator
     permission_classes = (permissions.ApplicationTokenPermission,)
 
     def get_queryset(self):
@@ -87,9 +89,9 @@ class ApplicationToken(ModelCrudViewSet):
         auth_code = request.DATA.get("auth_code", None)
         state = request.DATA.get("state", None)
         application_token = get_object_or_404(models.ApplicationToken,
-                                                application__id=application_id,
-                                                auth_code=auth_code,
-                                                state=state)
+                                              application__id=application_id,
+                                              auth_code=auth_code,
+                                              state=state)
 
         application_token.generate_token()
         application_token.save()
diff --git a/taiga/external_apps/serializers.py b/taiga/external_apps/serializers.py
index 095465fd..12ed3bab 100644
--- a/taiga/external_apps/serializers.py
+++ b/taiga/external_apps/serializers.py
@@ -16,9 +16,8 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-import json
-
 from taiga.base.api import serializers
+from taiga.base.fields import Field
 
 from . import models
 from . import services
@@ -26,33 +25,27 @@ from . import services
 from django.utils.translation import ugettext as _
 
 
-class ApplicationSerializer(serializers.ModelSerializer):
-    class Meta:
-        model = models.Application
-        fields = ("id", "name", "web", "description", "icon_url")
+class ApplicationSerializer(serializers.LightSerializer):
+    id = Field()
+    name = Field()
+    web = Field()
+    description = Field()
+    icon_url = Field()
 
 
-class ApplicationTokenSerializer(serializers.ModelSerializer):
-    cyphered_token = serializers.CharField(source="cyphered_token", read_only=True)
-    next_url = serializers.CharField(source="next_url", read_only=True)
-    application = ApplicationSerializer(read_only=True)
-
-    class Meta:
-        model = models.ApplicationToken
-        fields = ("user", "id", "application", "auth_code", "next_url")
+class ApplicationTokenSerializer(serializers.LightSerializer):
+    id = Field()
+    user = Field(attr="user_id")
+    application = ApplicationSerializer()
+    auth_code = Field()
+    next_url = Field()
 
 
-class AuthorizationCodeSerializer(serializers.ModelSerializer):
-    next_url = serializers.CharField(source="next_url", read_only=True)
-    class Meta:
-        model = models.ApplicationToken
-        fields = ("auth_code", "state", "next_url")
+class AuthorizationCodeSerializer(serializers.LightSerializer):
+    state = Field()
+    auth_code = Field()
+    next_url = Field()
 
 
-class AccessTokenSerializer(serializers.ModelSerializer):
-    cyphered_token = serializers.CharField(source="cyphered_token", read_only=True)
-    next_url = serializers.CharField(source="next_url", read_only=True)
-
-    class Meta:
-        model = models.ApplicationToken
-        fields = ("cyphered_token", )
+class AccessTokenSerializer(serializers.LightSerializer):
+    cyphered_token = Field()
diff --git a/taiga/external_apps/validators.py b/taiga/external_apps/validators.py
new file mode 100644
index 00000000..b2f2354d
--- /dev/null
+++ b/taiga/external_apps/validators.py
@@ -0,0 +1,54 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2014-2016 Andrey Antukh <niwi@niwi.nz>
+# Copyright (C) 2014-2016 Jesús Espino <jespinog@gmail.com>
+# Copyright (C) 2014-2016 David Barragán <bameda@dbarragan.com>
+# Copyright (C) 2014-2016 Alejandro Alonso <alejandro.alonso@kaleidos.net>
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from taiga.base.api import serializers
+
+from . import models
+from taiga.base.api import validators
+
+
+class ApplicationValidator(validators.ModelValidator):
+    class Meta:
+        model = models.Application
+        fields = ("id", "name", "web", "description", "icon_url")
+
+
+class ApplicationTokenValidator(validators.ModelValidator):
+    cyphered_token = serializers.CharField(source="cyphered_token", read_only=True)
+    next_url = serializers.CharField(source="next_url", read_only=True)
+    application = ApplicationValidator(read_only=True)
+
+    class Meta:
+        model = models.ApplicationToken
+        fields = ("user", "id", "application", "auth_code", "next_url")
+
+
+class AuthorizationCodeValidator(validators.ModelValidator):
+    next_url = serializers.CharField(source="next_url", read_only=True)
+    class Meta:
+        model = models.ApplicationToken
+        fields = ("auth_code", "state", "next_url")
+
+
+class AccessTokenValidator(validators.ModelValidator):
+    cyphered_token = serializers.CharField(source="cyphered_token", read_only=True)
+    next_url = serializers.CharField(source="next_url", read_only=True)
+
+    class Meta:
+        model = models.ApplicationToken
+        fields = ("cyphered_token", )