diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 ## [Unreleased]
 
+## [1.3.0] - 2024-06-13
+
+### Changed
+- Simplify core API (breaking change) (#47)
+
 ## [1.2.0] - 2024-03-18
 
 ### Added
@@ -82,7 +87,8 @@
 - Automated tests
 - Documentation
 
-[Unreleased]: https://github.com/haskell-webgear/webgear/compare/v1.2.0...HEAD
+[Unreleased]: https://github.com/haskell-webgear/webgear/compare/v1.3.0...HEAD
+[1.3.0]: https://github.com/haskell-webgear/webgear/releases/tag/v1.3.0
 [1.2.0]: https://github.com/haskell-webgear/webgear/releases/tag/v1.2.0
 [1.1.1]: https://github.com/haskell-webgear/webgear/releases/tag/v1.1.1
 [1.1.0]: https://github.com/haskell-webgear/webgear/releases/tag/v1.1.0
diff --git a/src/WebGear/Server/Trait/Auth/Basic.hs b/src/WebGear/Server/Trait/Auth/Basic.hs
--- a/src/WebGear/Server/Trait/Auth/Basic.hs
+++ b/src/WebGear/Server/Trait/Auth/Basic.hs
@@ -26,7 +26,7 @@
  )
 import WebGear.Server.Handler (ServerHandler)
 
-instance (Monad m) => Get (ServerHandler m) (BasicAuth' Required scheme m e a) Request where
+instance (Monad m) => Get (ServerHandler m) (BasicAuth' Required scheme m e a) where
   {-# INLINE getTrait #-}
   getTrait ::
     (HasTrait (AuthorizationHeader scheme) ts) =>
@@ -53,7 +53,7 @@
         res <- toBasicAttribute creds
         pure $ first BasicAuthAttributeError res
 
-instance (Monad m) => Get (ServerHandler m) (BasicAuth' Optional scheme m e a) Request where
+instance (Monad m) => Get (ServerHandler m) (BasicAuth' Optional scheme m e a) where
   {-# INLINE getTrait #-}
   getTrait ::
     (HasTrait (AuthorizationHeader scheme) ts) =>
diff --git a/src/WebGear/Server/Trait/Auth/JWT.hs b/src/WebGear/Server/Trait/Auth/JWT.hs
--- a/src/WebGear/Server/Trait/Auth/JWT.hs
+++ b/src/WebGear/Server/Trait/Auth/JWT.hs
@@ -22,7 +22,7 @@
 import WebGear.Core.Trait.Auth.JWT (JWTAuth' (..), JWTAuthError (..))
 import WebGear.Server.Handler (ServerHandler)
 
-instance (MonadTime m, Get (ServerHandler m) (AuthorizationHeader scheme) Request) => Get (ServerHandler m) (JWTAuth' Required scheme m e a) Request where
+instance (MonadTime m, Get (ServerHandler m) (AuthorizationHeader scheme)) => Get (ServerHandler m) (JWTAuth' Required scheme m e a) where
   {-# INLINE getTrait #-}
   getTrait ::
     (HasTrait (AuthorizationHeader scheme) ts) =>
@@ -46,7 +46,7 @@
         claims <- withExceptT JWTAuthTokenBadFormat $ JWT.verifyClaims jwtValidationSettings jwkSet jwt
         lift (toJWTAttribute claims) >>= either (throwError . JWTAuthAttributeError) pure
 
-instance (MonadTime m, Get (ServerHandler m) (AuthorizationHeader scheme) Request) => Get (ServerHandler m) (JWTAuth' Optional scheme m e a) Request where
+instance (MonadTime m, Get (ServerHandler m) (AuthorizationHeader scheme)) => Get (ServerHandler m) (JWTAuth' Optional scheme m e a) where
   {-# INLINE getTrait #-}
   getTrait ::
     (HasTrait (AuthorizationHeader scheme) ts) =>
diff --git a/src/WebGear/Server/Trait/Body.hs b/src/WebGear/Server/Trait/Body.hs
--- a/src/WebGear/Server/Trait/Body.hs
+++ b/src/WebGear/Server/Trait/Body.hs
@@ -16,12 +16,12 @@
 import WebGear.Server.Handler (ServerHandler (..))
 import WebGear.Server.MIMETypes (BodyRender (..), BodyUnrender (..))
 
-instance (Monad m, BodyUnrender m mt val) => Get (ServerHandler m) (Body mt val) Request where
+instance (Monad m, BodyUnrender m mt val) => Get (ServerHandler m) (Body mt val) where
   {-# INLINE getTrait #-}
   getTrait :: Body mt val -> ServerHandler m (Request `With` ts) (Either Text val)
   getTrait (Body mt) = arrM $ bodyUnrender mt . unwitness
 
-instance (Monad m, BodyRender m mt val) => Set (ServerHandler m) (Body mt val) Response where
+instance (Monad m, BodyRender m mt val) => Set (ServerHandler m) (Body mt val) where
   {-# INLINE setTrait #-}
   setTrait ::
     Body mt val ->
@@ -45,7 +45,7 @@
       | n == HTTP.hContentType = (HTTP.hContentType, mtStr) : hdrs
       | otherwise = (n, v) : go hdrs
 
-instance (Monad m) => Set (ServerHandler m) UnknownContentBody Response where
+instance (Monad m) => Set (ServerHandler m) UnknownContentBody where
   {-# INLINE setTrait #-}
   setTrait ::
     UnknownContentBody ->
diff --git a/src/WebGear/Server/Trait/Cookie.hs b/src/WebGear/Server/Trait/Cookie.hs
--- a/src/WebGear/Server/Trait/Cookie.hs
+++ b/src/WebGear/Server/Trait/Cookie.hs
@@ -21,7 +21,7 @@
 import WebGear.Core.Trait.Cookie (Cookie (..), CookieNotFound (..), CookieParseError (..), SetCookie (..))
 import WebGear.Server.Handler (ServerHandler)
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (Cookie Required name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (Cookie Required name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     Cookie Required name val ->
@@ -33,7 +33,7 @@
         Just (Left e) -> Left $ Right $ CookieParseError e
         Just (Right x) -> Right x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (Cookie Optional name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (Cookie Optional name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     Cookie Optional name val ->
@@ -60,7 +60,7 @@
 
   returnA -< parseHeader <$> lookupCookie
 
-instance (Monad m, KnownSymbol name) => Set (ServerHandler m) (SetCookie Required name) Response where
+instance (Monad m, KnownSymbol name) => Set (ServerHandler m) (SetCookie Required name) where
   {-# INLINE setTrait #-}
   setTrait ::
     SetCookie Required name ->
@@ -75,7 +75,7 @@
             _ -> response
     returnA -< f l response' cookie
 
-instance (Monad m, KnownSymbol name) => Set (ServerHandler m) (SetCookie Optional name) Response where
+instance (Monad m, KnownSymbol name) => Set (ServerHandler m) (SetCookie Optional name) where
   {-# INLINE setTrait #-}
   -- If the optional value is 'Nothing', the cookie is removed from the response
   setTrait ::
diff --git a/src/WebGear/Server/Trait/Header.hs b/src/WebGear/Server/Trait/Header.hs
--- a/src/WebGear/Server/Trait/Header.hs
+++ b/src/WebGear/Server/Trait/Header.hs
@@ -29,7 +29,7 @@
   let headerName :: HeaderName = fromString $ symbolVal proxy
   returnA -< parseHeader <$> requestHeader headerName (unwitness req)
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Required Strict name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Required Strict name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     RequestHeader Required Strict name val ->
@@ -41,7 +41,7 @@
         Just (Left e) -> Left $ Right $ HeaderParseError e
         Just (Right x) -> Right x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Optional Strict name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Optional Strict name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     RequestHeader Optional Strict name val ->
@@ -53,7 +53,7 @@
         Just (Left e) -> Left $ HeaderParseError e
         Just (Right x) -> Right $ Just x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Required Lenient name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Required Lenient name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     RequestHeader Required Lenient name val ->
@@ -65,7 +65,7 @@
         Just (Left e) -> Right $ Left e
         Just (Right x) -> Right $ Right x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Optional Lenient name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (RequestHeader Optional Lenient name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     RequestHeader Optional Lenient name val ->
@@ -77,7 +77,7 @@
         Just (Left e) -> Right $ Just $ Left e
         Just (Right x) -> Right $ Just $ Right x
 
-instance (Monad m, KnownSymbol name, ToHttpApiData val) => Set (ServerHandler m) (ResponseHeader Required name val) Response where
+instance (Monad m, KnownSymbol name, ToHttpApiData val) => Set (ServerHandler m) (ResponseHeader Required name val) where
   {-# INLINE setTrait #-}
   setTrait ::
     ResponseHeader Required name val ->
@@ -92,7 +92,7 @@
             _ -> response
     returnA -< f l response' val
 
-instance (Monad m, KnownSymbol name, ToHttpApiData val) => Set (ServerHandler m) (ResponseHeader Optional name val) Response where
+instance (Monad m, KnownSymbol name, ToHttpApiData val) => Set (ServerHandler m) (ResponseHeader Optional name val) where
   {-# INLINE setTrait #-}
   -- If the optional value is 'Nothing', the header is removed from the response
   setTrait ::
diff --git a/src/WebGear/Server/Trait/Method.hs b/src/WebGear/Server/Trait/Method.hs
--- a/src/WebGear/Server/Trait/Method.hs
+++ b/src/WebGear/Server/Trait/Method.hs
@@ -10,7 +10,7 @@
 import WebGear.Core.Trait.Method (Method (..), MethodMismatch (..))
 import WebGear.Server.Handler (ServerHandler)
 
-instance (Monad m) => Get (ServerHandler m) Method Request where
+instance (Monad m) => Get (ServerHandler m) Method where
   {-# INLINE getTrait #-}
   getTrait :: Method -> ServerHandler m (Request `With` ts) (Either MethodMismatch HTTP.StdMethod)
   getTrait (Method method) = proc request -> do
diff --git a/src/WebGear/Server/Trait/Path.hs b/src/WebGear/Server/Trait/Path.hs
--- a/src/WebGear/Server/Trait/Path.hs
+++ b/src/WebGear/Server/Trait/Path.hs
@@ -18,7 +18,7 @@
  )
 import WebGear.Server.Handler (ServerHandler (..))
 
-instance (Monad m) => Get (ServerHandler m) Path Request where
+instance (Monad m) => Get (ServerHandler m) Path where
   {-# INLINE getTrait #-}
   getTrait :: Path -> ServerHandler m (Request `With` ts) (Either () ())
   getTrait (Path p) = ServerHandler $ const $ do
@@ -28,7 +28,7 @@
       Just ps -> put (RoutePath ps) >> pure (Right ())
       Nothing -> pure (Left ())
 
-instance (Monad m, FromHttpApiData val) => Get (ServerHandler m) (PathVar tag val) Request where
+instance (Monad m, FromHttpApiData val) => Get (ServerHandler m) (PathVar tag val) where
   {-# INLINE getTrait #-}
   getTrait :: PathVar tag val -> ServerHandler m (Request `With` ts) (Either PathVarError val)
   getTrait PathVar = ServerHandler $ const $ do
@@ -40,14 +40,14 @@
           Left e -> pure (Left $ PathVarParseError e)
           Right val -> put (RoutePath ps) >> pure (Right val)
 
-instance (Monad m) => Get (ServerHandler m) PathEnd Request where
+instance (Monad m) => Get (ServerHandler m) PathEnd where
   {-# INLINE getTrait #-}
   getTrait :: PathEnd -> ServerHandler m (Request `With` ts) (Either () ())
   getTrait PathEnd =
-    ServerHandler
-      $ const
-      $ gets
-        ( \case
-            RoutePath [] -> Right ()
-            _ -> Left ()
-        )
+    ServerHandler $
+      const $
+        gets
+          ( \case
+              RoutePath [] -> Right ()
+              _ -> Left ()
+          )
diff --git a/src/WebGear/Server/Trait/QueryParam.hs b/src/WebGear/Server/Trait/QueryParam.hs
--- a/src/WebGear/Server/Trait/QueryParam.hs
+++ b/src/WebGear/Server/Trait/QueryParam.hs
@@ -31,7 +31,7 @@
       params = queryToQueryText $ queryString $ unwitness req
   returnA -< parseQueryParam <$> (find ((== name) . fst) params >>= snd)
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Required Strict name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Required Strict name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     QueryParam Required Strict name val ->
@@ -43,7 +43,7 @@
         Just (Left e) -> Left $ Right $ ParamParseError e
         Just (Right x) -> Right x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Optional Strict name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Optional Strict name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     QueryParam Optional Strict name val ->
@@ -55,7 +55,7 @@
         Just (Left e) -> Left $ ParamParseError e
         Just (Right x) -> Right $ Just x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Required Lenient name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Required Lenient name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     QueryParam Required Lenient name val ->
@@ -67,7 +67,7 @@
         Just (Left e) -> Right $ Left e
         Just (Right x) -> Right $ Right x
 
-instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Optional Lenient name val) Request where
+instance (Monad m, KnownSymbol name, FromHttpApiData val) => Get (ServerHandler m) (QueryParam Optional Lenient name val) where
   {-# INLINE getTrait #-}
   getTrait ::
     QueryParam Optional Lenient name val ->
diff --git a/src/WebGear/Server/Trait/Status.hs b/src/WebGear/Server/Trait/Status.hs
--- a/src/WebGear/Server/Trait/Status.hs
+++ b/src/WebGear/Server/Trait/Status.hs
@@ -10,7 +10,7 @@
 import WebGear.Core.Trait.Status (Status (..))
 import WebGear.Server.Handler (ServerHandler)
 
-instance (Monad m) => Set (ServerHandler m) Status Response where
+instance (Monad m) => Set (ServerHandler m) Status where
   {-# INLINE setTrait #-}
   setTrait ::
     Status ->
diff --git a/webgear-server.cabal b/webgear-server.cabal
--- a/webgear-server.cabal
+++ b/webgear-server.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.4
 name:                webgear-server
-version:             1.2.0
+version:             1.3.0
 synopsis:            Composable, type-safe library to build HTTP API servers
 description:
     WebGear is a library to for building composable, type-safe HTTP API servers.
@@ -59,7 +59,7 @@
                     , http-types ==0.12.*
                     , text >=1.2.0.0 && <2.2
                     , wai ==3.2.*
-                    , webgear-core ^>=1.2.0
+                    , webgear-core ^>=1.3.0
   ghc-options:        -Wall
                       -Wno-unticked-promoted-constructors
                       -Wcompat