diff --git a/mig-extra/src/Mig/Extra/Server/Json.hs b/mig-extra/src/Mig/Extra/Server/Json.hs
index 212d43e..a37647c 100644
--- a/mig-extra/src/Mig/Extra/Server/Json.hs
+++ b/mig-extra/src/Mig/Extra/Server/Json.hs
@@ -21,7 +21,8 @@ module Mig.Extra.Server.Json (
 
   -- * re-exports
   module X,
-) where
+)
+where
 
 import Mig.Client (FromClient (..), ToClient (..))
 import Mig.Core (
@@ -57,11 +58,6 @@ instance (ToSchema a, FromJSON a, ToRoute b) => ToRoute (Body a -> b) where
     (toRouteFun :: ((Core.Body Json a -> b) -> ServerFun (Core.MonadOf b)))
       (\(Core.Body a) -> f (Body a))
 
-instance (ToSchema a, FromJSON a, ToRoute b) => ToServer (Body a -> b) where
-  toServer f =
-    (toServer :: ((Core.Body Json a -> b) -> Server (Core.MonadOf b)))
-      (\(Core.Body a) -> f (Body a))
-
 instance (FromJSON a, ToSchema a, ToPlugin b) => ToPlugin (Body a -> b) where
   toPluginInfo = toPluginInfo @(Core.Body Json a -> b)
 
diff --git a/mig/src/Mig/Core/Class/Server.hs b/mig/src/Mig/Core/Class/Server.hs
index 1a6ff50..a79b1fb 100644
--- a/mig/src/Mig/Core/Class/Server.hs
+++ b/mig/src/Mig/Core/Class/Server.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE UndecidableInstances #-}
+
 -- | To server class
 module Mig.Core.Class.Server (
   (/.),
@@ -11,18 +13,13 @@ module Mig.Core.Class.Server (
 import Control.Monad.Except (ExceptT, runExceptT)
 import Control.Monad.Reader
 import Data.Kind
-import Data.OpenApi (ToParamSchema, ToSchema)
 import Data.Text (Text)
-import GHC.TypeLits
 import Mig.Core.Api qualified as Api
-import Mig.Core.Class.MediaType (FromReqBody (..))
 import Mig.Core.Class.Monad
-import Mig.Core.Class.Response (IsResp)
 import Mig.Core.Class.Route
 import Mig.Core.Server (Server (..), mapServerFun)
 import Mig.Core.ServerFun (ServerFun)
 import Mig.Core.Types
-import Web.HttpApiData
 
 infixr 4 /.
 
@@ -66,28 +63,8 @@ instance ToServer (Server m) where
 instance (ToServer a) => ToServer [a] where
   toServer = foldMap toServer
 
--- outputs
-instance (MonadIO m, IsResp a, IsMethod method) => ToServer (Send method m a) where
-  toServer a = Server $ Api.HandleRoute (toRoute a)
-
--- inputs
-
-instance (ToSchema a, FromReqBody media a, ToRoute b) => ToServer (Body media a -> b) where
-  toServer a = Server $ Api.HandleRoute (toRoute a)
-
-instance (FromHttpApiData a, ToParamSchema a, ToRoute b, KnownSymbol sym) => ToServer (Query sym a -> b) where
-  toServer a = Server $ Api.HandleRoute (toRoute a)
-
-instance (FromHttpApiData a, ToParamSchema a, ToRoute b, KnownSymbol sym) => ToServer (Optional sym a -> b) where
-  toServer a = Server $ Api.HandleRoute (toRoute a)
-
-instance (FromHttpApiData a, ToParamSchema a, ToRoute b, KnownSymbol sym) => ToServer (Capture sym a -> b) where
-  toServer a = Server $ Api.HandleRoute (toRoute a)
-
-instance (FromHttpApiData a, ToParamSchema a, ToRoute b, KnownSymbol sym) => ToServer (Header sym a -> b) where
-  toServer a = Server $ Api.HandleRoute (toRoute a)
-
-instance (ToRoute b) => ToServer (PathInfo -> b) where
+-- routes
+instance {-# OVERLAPPABLE #-} (ToRoute a) => ToServer a where
   toServer a = Server $ Api.HandleRoute (toRoute a)
 
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