diff --git a/etebase_fastapi/authentication.py b/etebase_fastapi/authentication.py
index 3ae6c4b..287b46e 100644
--- a/etebase_fastapi/authentication.py
+++ b/etebase_fastapi/authentication.py
@@ -18,15 +18,16 @@ from fastapi import APIRouter, Depends, status, Request, Response
 from fastapi.security import APIKeyHeader
 from pydantic import BaseModel
 
-from django_etebase import app_settings
+from django_etebase import app_settings, models
 from django_etebase.exceptions import EtebaseValidationError
 from django_etebase.models import UserInfo
 from django_etebase.serializers import UserSerializer
+from django_etebase.signals import user_signed_up
 from django_etebase.token_auth.models import AuthToken
 from django_etebase.token_auth.models import get_default_expiry
 from django_etebase.utils import create_user
 from django_etebase.views import msgpack_encode, msgpack_decode
-from .execptions import AuthenticationFailed
+from .execptions import AuthenticationFailed, transform_validation_error, ValidationError
 from .msgpack import MsgpackResponse, MsgpackRoute
 
 User = get_user_model()
@@ -272,7 +273,7 @@ async def change_password(data: ChangePassword, request: Request, user: User = D
 
 
 @sync_to_async
-def signup_save(data: SignupIn):
+def signup_save(data: SignupIn) -> User:
     user_data = data.user
     with transaction.atomic():
         try:
@@ -290,17 +291,26 @@ def signup_save(data: SignupIn):
             except EtebaseValidationError as e:
                 raise e
             except django_exceptions.ValidationError as e:
-                self.transform_validation_error("user", e)
+                transform_validation_error("user", e)
             except Exception as e:
                 raise EtebaseValidationError("generic", str(e))
 
         if hasattr(instance, "userinfo"):
-            raise EtebaseValidationError("user_exists", "User already exists", status_code=status.HTTP_409_CONFLICT)
+            raise ValidationError("user_exists", "User already exists", status_code=status.HTTP_409_CONFLICT)
 
-        models.UserInfo.objects.create(**validated_data, owner=instance)
+        models.UserInfo.objects.create(**data.dict(exclude={"user"}), owner=instance)
     return instance
 
 
+@sync_to_async
+def send_user_signed_up_async(user: User, request):
+    user_signed_up.send(sender=user.__class__, request=request, user=user)
+
+
 @authentication_router.post("/signup/")
 async def signup(data: SignupIn):
-    pass
+    user = await signup_save(data)
+    # XXX-TOM
+    data = await login_response_data(user)
+    await send_user_signed_up_async(user, None)
+    return MsgpackResponse(content=data, status_code=status.HTTP_201_CREATED)
diff --git a/etebase_fastapi/execptions.py b/etebase_fastapi/execptions.py
index 2b35634..fa76c45 100644
--- a/etebase_fastapi/execptions.py
+++ b/etebase_fastapi/execptions.py
@@ -1,8 +1,23 @@
 from fastapi import status
+import typing as t
+
+from pydantic import BaseModel
 
 from django_etebase.exceptions import EtebaseValidationError
 
 
+class ValidationErrorField(BaseModel):
+    field: str
+    code: str
+    detail: str
+
+
+class ValidationErrorOut(BaseModel):
+    code: str
+    detail: str
+    errors: t.Optional[t.List[ValidationErrorField]]
+
+
 class CustomHttpException(Exception):
     def __init__(self, code: str, detail: str, status_code: int = status.HTTP_400_BAD_REQUEST):
         self.status_code = status_code
@@ -44,12 +59,27 @@ class PermissionDenied(CustomHttpException):
         super().__init__(code=code, detail=detail, status_code=status_code)
 
 
+from django_etebase.exceptions import EtebaseValidationError
+
+
 class ValidationError(CustomHttpException):
-    def __init__(self, code: str, detail: str, status_code: int = status.HTTP_400_BAD_REQUEST):
+    def __init__(
+        self,
+        code: str,
+        detail: str,
+        status_code: int = status.HTTP_400_BAD_REQUEST,
+        field: t.Optional[str] = None,
+        errors: t.Optional[t.List["ValidationError"]] = None,
+    ):
+        self.errors = errors
         super().__init__(code=code, detail=detail, status_code=status_code)
 
+    @property
+    def as_dict(self) -> dict:
+        return ValidationErrorOut(code=self.code, errors=self.errors, detail=self.detail).dict()
+
 
-def flatten_errors(field_name, errors):
+def flatten_errors(field_name, errors) -> t.List[ValidationError]:
     ret = []
     if isinstance(errors, dict):
         for error_key in errors:
@@ -61,13 +91,7 @@ def flatten_errors(field_name, errors):
                 message = error.messages[0]
             else:
                 message = str(error)
-            ret.append(
-                {
-                    "field": field_name,
-                    "code": error.code,
-                    "detail": message,
-                }
-            )
+            ret.append(dict(code=error.code, detail=message, field=field_name))
     return ret
 
 
@@ -78,11 +102,4 @@ def transform_validation_error(prefix, err):
         errors = flatten_errors(prefix, err.error_list)
     else:
         raise EtebaseValidationError(err.code, err.message)
-    raise ValidationError(code="field_errors", detail="Field validations failed.")
-    raise serializers.ValidationError(
-        {
-            "code": "field_errors",
-            "detail": "Field validations failed.",
-            "errors": errors,
-        }
-    )
+    raise ValidationError(code="field_errors", detail="Field validations failed.", errors=errors)