diff --git a/src/Data/Opentracing/Tracer.hs b/src/Data/Opentracing/Tracer.hs
--- a/src/Data/Opentracing/Tracer.hs
+++ b/src/Data/Opentracing/Tracer.hs
@@ -17,11 +17,8 @@
 import           Control.Monad.IO.Class
 import qualified Data.HashMap.Lazy      as HM
 import           Data.Opentracing.Types
-import           Data.Text              (Text, justifyRight, pack)
 import           Data.Time.Clock.POSIX
-import           Data.Word
-import           Numeric
-import           System.Random
+import           Yam.Types.Prelude
 
 type SpanName = Text
 
@@ -31,12 +28,6 @@
 class MonadTracer m => MonadTracing m where
   runInSpan :: SpanName -> (Span -> m ()) -> (Span -> m a) ->  m a
 
-{-# INLINE newId #-}
-newId :: MonadIO m => m Text
-newId = liftIO $ do
-  c <- randomIO :: IO Word64
-  return $ justifyRight 16 '0' $ pack $ showHex c ""
-
 newSpan :: MonadTracer m => SpanName -> m Span
 newSpan name = do
   context     <- askSpanContext
@@ -44,11 +35,11 @@
 
 
 getNow :: MonadIO m => m Int
-getNow = liftIO $ (round . (* 1000)) <$> getPOSIXTime
+getNow = liftIO $ round . (* 1000) <$> getPOSIXTime
 
 newSpan' :: MonadTracer m => SpanName -> SpanContext -> [SpanReference] -> m Span
 newSpan' name context references = do
-  spanId      <- if null references then return (traceId context) else newId
+  spanId      <- if null references then return (traceId context) else liftIO randomString
   startTime   <- getNow
   let finishTime = Nothing
       tags       = HM.empty
@@ -82,6 +73,6 @@
 
 newContext :: MonadIO m => m SpanContext
 newContext = do
-  traceId <- newId
+  traceId <- liftIO randomString
   let baggage = HM.empty
   return SpanContext{..}
diff --git a/src/Data/Opentracing/Types.hs b/src/Data/Opentracing/Types.hs
--- a/src/Data/Opentracing/Types.hs
+++ b/src/Data/Opentracing/Types.hs
@@ -1,5 +1,6 @@
 module Data.Opentracing.Types where
 
+import           Data.ByteString   (ByteString)
 import qualified Data.HashMap.Lazy as HM
 import           Data.Scientific
 import           Data.Text         (Text)
@@ -11,7 +12,7 @@
   deriving (Eq, Show)
 
 data SpanContext = SpanContext
-  { traceId :: Text
+  { traceId :: ByteString
   , baggage :: HM.HashMap Text (Maybe Text)
   } deriving (Eq, Show)
 
@@ -22,11 +23,11 @@
 
 data SpanReference = SpanReference
   { referenceType :: SpanReferenceType
-  , parentId      :: Text
+  , parentId      :: ByteString
   } deriving (Eq, Show)
 
 data Span = Span
-  { spanId     :: Text
+  { spanId     :: ByteString
   , name       :: Text
   , startTime  :: Int
   , finishTime :: Maybe Int
diff --git a/src/Yam/Internal.hs b/src/Yam/Internal.hs
--- a/src/Yam/Internal.hs
+++ b/src/Yam/Internal.hs
@@ -74,7 +74,7 @@
   -> ServerT api App
   -> IO ()
 start p = startYam
-  (readConfig "yam.application" p)
-  (readConfig "yam.swagger"     p)
-  (readConfig "yam.logging"     p)
-  (readConfig "yam.trace"       p)
+  (p .>> "yam.application")
+  (p .>> "yam.swagger"    )
+  (p .>> "yam.logging"    )
+  (p .>> "yam.trace"      )
diff --git a/src/Yam/Logger.hs b/src/Yam/Logger.hs
--- a/src/Yam/Logger.hs
+++ b/src/Yam/Logger.hs
@@ -18,15 +18,17 @@
 import           Yam.Types.Env
 import           Yam.Types.Prelude
 
-instance FromJSON LogLevel where
-  parseJSON v = go . T.toLower <$> parseJSON v
+instance FromProperties LogLevel where
+  fromProperties = fromProperties >=> go
     where
-      go :: Text -> LogLevel
-      go "debug" = LevelDebug
-      go "info"  = LevelInfo
-      go "warn"  = LevelWarn
-      go "error" = LevelError
-      go level   = LevelOther level
+      go :: Property -> Return LogLevel
+      go (PStr t) = OK (gt $ T.toLower t)
+      go _        = Fail "loglevel shoudbe string"
+      gt "debug" = LevelDebug
+      gt "info"  = LevelInfo
+      gt "warn"  = LevelWarn
+      gt "error" = LevelError
+      gt _       = LevelOther "fatal"
 
 {-# INLINE toStr #-}
 toStr :: LogLevel -> LogStr
@@ -45,15 +47,15 @@
   } deriving (Eq, Show)
 
 instance Default LogConfig where
-  def = defJson
+  def = LogConfig 4096 "" 10485760 256 LevelInfo
 
-instance FromJSON LogConfig where
-  parseJSON = withObject "LogConfig" $ \v -> LogConfig
-    <$> v .:? "buffer-size" .!= 4096
-    <*> v .:? "file"        .!= ""
-    <*> v .:? "max-size"    .!= 10485760
-    <*> v .:? "max-history" .!= 256
-    <*> v .:? "level"       .!= LevelInfo
+instance FromProperties LogConfig where
+  fromProperties p = LogConfig
+    <$> p .?> "buffer-size" .?= bufferSize    def
+    <*> p .?> "file"        .?= file          def
+    <*> p .?> "max-size"    .?= maxSize       def
+    <*> p .?> "max-history" .?= rotateHistory def
+    <*> p .?> "level"       .?= level         def
 
 newLogger :: Text -> LogConfig -> IO (LogFunc, IO ())
 newLogger name LogConfig{..} = do
diff --git a/src/Yam/Middleware/Trace.hs b/src/Yam/Middleware/Trace.hs
--- a/src/Yam/Middleware/Trace.hs
+++ b/src/Yam/Middleware/Trace.hs
@@ -27,16 +27,16 @@
   = NoTracer
   deriving (Eq, Show)
 
-instance FromJSON TraceNotifyType where
-  parseJSON v = go . T.toLower <$> parseJSON v
+instance FromProperties TraceNotifyType where
+  fromProperties = fromProperties >=> go
     where
-      go :: Text -> TraceNotifyType
-      go _ = NoTracer
+      go :: Property -> Return TraceNotifyType
+      go _ = OK NoTracer
 
-instance FromJSON TraceConfig where
-  parseJSON = withObject "TraceConfig" $ \v -> TraceConfig
-    <$> v .:? "enabled" .!= True
-    <*> v .:? "type"    .!= NoTracer
+instance FromProperties TraceConfig where
+  fromProperties p = TraceConfig
+    <$> p .?> "enabled" .?= enabled def
+    <*> p .?> "type"    .?= method  def
 
 instance Default TraceConfig where
   def = TraceConfig True NoTracer
@@ -82,10 +82,10 @@
 parseSpan headers env =
   let sc = fromMaybe (SpanContext "" HM.empty) $ getAttr spanContextKey env
   in case lookup hTraceId headers of
-      Just tid -> let sc' = sc { traceId = decodeUtf8 tid }
+      Just tid -> let sc' = sc { traceId = tid }
                   in return $ env
                       & setAttr spanContextKey      sc'
-                      & go (maybe (traceId sc') decodeUtf8 $ lookup hSpanId headers) sc'
+                      & go (fromMaybe (traceId sc') $ lookup hSpanId headers) sc'
       _        -> do
         c <- newContext
         return $ setAttr spanContextKey c env
@@ -103,13 +103,13 @@
 traceMw env' notify app req resH = do
   env <- parseSpan (requestHeaders req) env'
   runApp env $
-    runInSpan ((decodeUtf8 $ requestMethod req) <> " /" <> T.intercalate "/" (pathInfo req)) notify $ \s@Span{..} -> do
+    runInSpan (decodeUtf8 (requestMethod req) <> " /" <> T.intercalate "/" (pathInfo req)) notify $ \s@Span{..} -> do
       let SpanContext{..} = context
-          tid = traceId <> "," <> spanId
+          tid = decodeUtf8 $ traceId <> "," <> spanId
           v   = L.insert extensionLogKey tid (vault req)
           v'  = L.insert spanKey s v
       liftIO $ app req {vault = v'}
-        $ resH . mapResponseHeaders (\hs -> (hTraceId,encodeUtf8 traceId):(hSpanId, encodeUtf8 spanId):hs)
+        $ resH . mapResponseHeaders (\hs -> (hTraceId, traceId):(hSpanId, spanId):hs)
 
 traceMiddleware :: TraceConfig -> AppMiddleware
 traceMiddleware TraceConfig{..}
diff --git a/src/Yam/Swagger.hs b/src/Yam/Swagger.hs
--- a/src/Yam/Swagger.hs
+++ b/src/Yam/Swagger.hs
@@ -5,7 +5,7 @@
   , module Control.Lens
   ) where
 
-import           Control.Lens       hiding (Context, allOf, (.=))
+import           Control.Lens       hiding (Context, Empty, allOf, (.=))
 import           Data.Reflection
 import           Data.Swagger       hiding (name, port)
 import qualified Data.Swagger       as S
@@ -23,13 +23,13 @@
   } deriving (Eq, Show)
 
 instance Default SwaggerConfig where
-  def = defJson
+  def = SwaggerConfig "swagger-ui" "swagger-ui.json" True
 
-instance FromJSON SwaggerConfig where
-  parseJSON = withObject "SwaggerConfig" $ \v -> SwaggerConfig
-    <$> v .:? "dir"     .!= "swagger-ui"
-    <*> v .:? "schema"  .!= "swagger-ui.json"
-    <*> v .:? "enabled" .!= True
+instance FromProperties SwaggerConfig where
+  fromProperties p = SwaggerConfig
+    <$> p .?> "dir"     .?= urlDir    def
+    <*> p .?> "schema"  .?= urlSchema def
+    <*> p .?> "enabled" .?= enabled   def
 
 type SAPI dir schema api = SwaggerSchemaUI dir schema :<|> api
 
diff --git a/src/Yam/Types/Env.hs b/src/Yam/Types/Env.hs
--- a/src/Yam/Types/Env.hs
+++ b/src/Yam/Types/Env.hs
@@ -14,13 +14,13 @@
   , port :: Int
   } deriving (Eq, Show)
 
-instance FromJSON AppConfig where
-  parseJSON = withObject "AppConfig" $ \v -> AppConfig
-    <$> v .:? "name" .!= "application"
-    <*> v .:? "port" .!= 8888
+instance FromProperties AppConfig where
+  fromProperties p = AppConfig
+    <$> p .?> "name" .?= name def
+    <*> p .?> "port" .?= port def
 
 instance Default AppConfig where
-  def = defJson
+  def = AppConfig "application" 8888
 
 data Env = Env
   { attributes    :: Vault
@@ -32,7 +32,7 @@
   def = Env L.empty Nothing def
 
 getAttr :: Key a -> Env -> Maybe a
-getAttr k Env{..} = listToMaybe $ catMaybes $ L.lookup k <$> catMaybes [reqAttributes, Just attributes]
+getAttr k Env{..} = (reqAttributes >>= L.lookup k) <|> L.lookup k attributes
 
 reqAttr :: Default a => Key a -> Env -> a
 reqAttr k = fromMaybe def . getAttr k
diff --git a/src/Yam/Types/Prelude.hs b/src/Yam/Types/Prelude.hs
--- a/src/Yam/Types/Prelude.hs
+++ b/src/Yam/Types/Prelude.hs
@@ -1,8 +1,10 @@
 module Yam.Types.Prelude(
-    defJson
-  , randomString
+    randomString
   , showText
-  , readConfig
+  , (.>>)
+  , (.?>)
+  , (.?=)
+  , (.|=)
   , LogFunc
   , Default(..)
   , Text
@@ -18,12 +20,12 @@
   , module Data.Proxy
   , module Data.Vault.Lazy
   , module Data.Maybe
-  , module Data.Aeson
   , module Data.Word
   , module Data.Text.Encoding
   , module Data.Function
   , module Data.Salak
   , module Data.Version
+  , module Control.Applicative
   , module Control.Monad
   , module Control.Monad.Reader
   , module Control.Monad.Logger.CallStack
@@ -31,13 +33,17 @@
   , module Network.HTTP.Types
   ) where
 
+import           Control.Applicative
 import           Control.Exception              hiding (Handler)
 import           Control.Monad
 import           Control.Monad.Except
 import           Control.Monad.IO.Unlift
 import           Control.Monad.Logger.CallStack
 import           Control.Monad.Reader
-import           Data.Aeson
+import qualified Data.Binary                    as B
+import           Data.ByteString                (ByteString)
+import qualified Data.ByteString.Base16.Lazy    as B16
+import qualified Data.ByteString.Lazy           as L
 import           Data.Default
 import           Data.Function
 import           Data.Maybe
@@ -45,10 +51,12 @@
 import           Data.Salak
     ( FromProperties (..)
     , Properties
+    , Property (..)
+    , Return (..)
     , defaultPropertiesWithFile
     )
 import qualified Data.Salak                     as S
-import           Data.Text                      (Text, justifyRight, pack)
+import           Data.Text                      (Text, pack, unpack)
 import           Data.Text.Encoding             (decodeUtf8, encodeUtf8)
 import           Data.Vault.Lazy                (Key, Vault, newKey)
 import           Data.Version
@@ -56,24 +64,44 @@
 import           GHC.Stack
 import           Network.HTTP.Types
 import           Network.Wai
-import           Numeric
-import           System.Random
+import           System.IO.Unsafe               (unsafePerformIO)
+import           System.Random.MWC
 
+infixl 5 .?>
+(.?>) :: FromProperties a => Properties -> Text -> Return a
+(.?>) = flip S.lookup'
+
+infixl 5 .|=
+(.|=) :: Return a -> a -> a
+(.|=) (OK   a) _ = a
+(.|=) (Fail e) _ = error e
+(.|=) _        d = d
+
+infixl 5 .?=
+(.?=) :: Return a -> a -> Return a
+(.?=) a b = OK (a .|= b)
+
+infixl 5 .>>
+(.>>) :: FromProperties a => Properties -> Text -> a
+(.>>) p k = case p .?> k of
+  OK v   -> v
+  Empty  -> case fromProperties S.empty of
+    (OK   a) -> a
+    (Fail e) -> error e
+    _        -> error $ "Config " <> unpack k <> " not found"
+  Fail e -> error e
+
 type LogFunc = Loc -> LogSource -> LogLevel -> LogStr -> IO ()
 
-defJson :: FromJSON a => a
-defJson = fromJust $ decode "{}"
+{-# NOINLINE randomGen #-}
+randomGen :: GenIO
+randomGen = unsafePerformIO create
 
 -- | Utility
-{-# INLINE randomString #-}
-randomString :: Int -> IO Text
-randomString n = do
-  c <- randomIO :: IO Word64
-  return $ justifyRight n '0' $ pack $ take n $ showHex c ""
+randomString :: IO ByteString
+randomString = L.toStrict . B16.encode . B.encode <$> (uniform randomGen :: IO Word64)
 
 {-# INLINE showText #-}
 showText :: Show a => a -> Text
 showText = pack . show
 
-readConfig :: (Default a, FromProperties a) => Text -> Properties -> a
-readConfig k p = fromMaybe def $ S.lookup k p
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -4,7 +4,7 @@
 
 module Main where
 
-import qualified Data.Text               as T
+import qualified Data.ByteString         as B
 import           Test.Hspec
 import           Test.QuickCheck.Monadic
 import           Yam
@@ -19,5 +19,5 @@
   context "randomTest" $ do
     it "random" $ do
       monadicIO $ do
-        s <- run $ randomString 14
-        assert (T.length s == 14)
+        s <- run $ randomString
+        assert (B.length s == 16)
diff --git a/yam.cabal b/yam.cabal
--- a/yam.cabal
+++ b/yam.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.12
 name: yam
-version: 0.5.5
+version: 0.5.6
 license: BSD3
 license-file: LICENSE
 copyright: (c) 2018 Daniel YU
@@ -49,8 +49,9 @@
                  -Wincomplete-uni-patterns -Wredundant-constraints -fno-warn-orphans
                  -fno-warn-missing-signatures
     build-depends:
-        aeson >=1.4.2.0 && <1.5,
         base >=4.11 && <5,
+        base16-bytestring >=0.1.1.6 && <0.2,
+        binary >=0.8.6.0 && <0.9,
         bytestring >=0.10.8.2 && <0.11,
         data-default >=0.7.1.1 && <0.8,
         fast-logger >=2.4.13 && <2.5,
@@ -58,7 +59,7 @@
         lens ==4.17.*,
         monad-logger >=0.3.30 && <0.4,
         mtl >=2.2.2 && <2.3,
-        random ==1.1.*,
+        mwc-random >=0.14.0.0 && <0.15,
         reflection >=2.1.4 && <2.2,
         salak >=0.1.4 && <0.3,
         scientific >=0.3.6.2 && <0.4,
@@ -112,8 +113,9 @@
                  -fno-warn-missing-signatures
     build-depends:
         QuickCheck >=2.12.6.1 && <2.13,
-        aeson >=1.4.2.0 && <1.5,
         base >=4.11 && <5,
+        base16-bytestring >=0.1.1.6 && <0.2,
+        binary >=0.8.6.0 && <0.9,
         bytestring >=0.10.8.2 && <0.11,
         data-default >=0.7.1.1 && <0.8,
         fast-logger >=2.4.13 && <2.5,
@@ -122,7 +124,7 @@
         lens ==4.17.*,
         monad-logger >=0.3.30 && <0.4,
         mtl >=2.2.2 && <2.3,
-        random ==1.1.*,
+        mwc-random >=0.14.0.0 && <0.15,
         reflection >=2.1.4 && <2.2,
         salak >=0.1.4 && <0.3,
         scientific >=0.3.6.2 && <0.4,