diff --git a/yesod-auth/yesod-auth.cabal b/yesod-auth/yesod-auth.cabal
index 21f78a81..194638f5 100644
--- a/yesod-auth/yesod-auth.cabal
+++ b/yesod-auth/yesod-auth.cabal
@@ -58,7 +58,7 @@ library
                    , binary
                    , http-client
                    , blaze-builder
-                   , conduit
+                   , conduit                 >= 1.3
                    , conduit-extra
                    , nonce                   >= 1.0.2     && < 1.1
 
diff --git a/yesod-bin/Devel.hs b/yesod-bin/Devel.hs
index 4579064b..c60b17d6 100644
--- a/yesod-bin/Devel.hs
+++ b/yesod-bin/Devel.hs
@@ -17,9 +17,7 @@ import           Control.Monad                         (forever, unless, void,
                                                         when)
 import Data.ByteString (ByteString, isInfixOf)
 import qualified Data.ByteString.Lazy                  as LB
-import           Data.Conduit                          (($$), (=$))
-import qualified Data.Conduit.Binary                   as CB
-import qualified Data.Conduit.List                     as CL
+import           Conduit
 import           Data.Default.Class                    (def)
 import           Data.FileEmbed                        (embedFile)
 import qualified Data.Map                              as Map
@@ -368,9 +366,10 @@ devel opts passThroughArgs = do
         -- process is piped to the actual stdout and stderr handles.
         withProcess_ procConfig $ \p -> do
             let helper getter h =
-                      getter p
-                   $$ CL.iterM (\(str :: ByteString) -> atomically (updateAppPort str buildStarted appPortVar))
-                   =$ CB.sinkHandle h
+                      runConduit
+                    $ getter p
+                   .| iterMC (\(str :: ByteString) -> atomically (updateAppPort str buildStarted appPortVar))
+                   .| sinkHandle h
             race_ (helper getStdout stdout) (helper getStderr stderr)
 
     -- Run the inner action with a TVar which will be set to True
diff --git a/yesod-bin/HsFile.hs b/yesod-bin/HsFile.hs
index 38093a51..18868c24 100644
--- a/yesod-bin/HsFile.hs
+++ b/yesod-bin/HsFile.hs
@@ -2,20 +2,18 @@
 {-# LANGUAGE OverloadedStrings #-}
 module HsFile (mkHsFile) where
 import Text.ProjectTemplate (createTemplate)
-import Data.Conduit 
-    ( ($$), (=$), awaitForever)
-import Data.Conduit.Filesystem (sourceDirectory)
+import Conduit
 import Control.Monad.Trans.Resource (runResourceT)
-import qualified Data.Conduit.List as CL
 import qualified Data.ByteString as BS
 import Control.Monad.IO.Class (liftIO)
 import Data.String (fromString)
 
 mkHsFile :: IO ()
-mkHsFile = runResourceT $ sourceDirectory "."
-        $$ readIt
-        =$ createTemplate 
-        =$ awaitForever (liftIO . BS.putStr)
+mkHsFile = runConduitRes
+         $ sourceDirectory "."
+        .| readIt
+        .| createTemplate
+        .| mapM_C (liftIO . BS.putStr)
   where
     -- Reads a filepath from upstream and dumps a pair of (filepath, filecontents)
-    readIt = CL.map $ \i -> (fromString i, liftIO $ BS.readFile i)
+    readIt = mapC $ \i -> (fromString i, liftIO $ BS.readFile i)
diff --git a/yesod-core/Yesod/Core/Class/Yesod.hs b/yesod-core/Yesod/Core/Class/Yesod.hs
index 5e169d7e..2903654c 100644
--- a/yesod-core/Yesod/Core/Class/Yesod.hs
+++ b/yesod-core/Yesod/Core/Class/Yesod.hs
@@ -10,9 +10,8 @@ import           Yesod.Core.Handler
 
 import           Yesod.Routes.Class
 
-import           Blaze.ByteString.Builder           (Builder, toByteString)
-import           Blaze.ByteString.Builder.ByteString (copyByteString)
-import           Blaze.ByteString.Builder.Char.Utf8 (fromText, fromChar)
+import           Data.ByteString.Builder            (Builder, toLazyByteString)
+import           Data.Text.Encoding                 (encodeUtf8Builder)
 import           Control.Arrow                      ((***), second)
 import           Control.Exception                  (bracket)
 #if __GLASGOW_HASKELL__ < 710
@@ -25,6 +24,7 @@ import           Control.Monad.Logger               (LogLevel (LevelInfo, LevelO
 import           Control.Monad.Trans.Resource       (InternalState, createInternalState, closeInternalState)
 import qualified Data.ByteString.Char8              as S8
 import qualified Data.ByteString.Lazy               as L
+import qualified Data.ByteString.Lazy.Char8         as BL8
 import Data.Aeson (object, (.=))
 import           Data.List                          (foldl', nub)
 import qualified Data.Map                           as Map
@@ -113,10 +113,10 @@ class RenderRoute site => Yesod site where
     -- | Override the rendering function for a particular URL and query string
     -- parameters. One use case for this is to offload static hosting to a
     -- different domain name to avoid sending cookies.
-    -- 
+    --
     -- For backward compatibility default implementation is in terms of
     -- 'urlRenderOverride', probably ineffective
-    -- 
+    --
     -- Since 1.4.23
     urlParamRenderOverride :: site
                            -> Route site
@@ -126,11 +126,11 @@ class RenderRoute site => Yesod site where
       where
         addParams [] routeBldr = routeBldr
         addParams nonEmptyParams routeBldr =
-            let routeBS = toByteString routeBldr
-                qsSeparator = fromChar $ if S8.elem '?' routeBS then '&' else '?'
+            let routeBS = toLazyByteString routeBldr
+                qsSeparator = if BL8.elem '?' routeBS then "&" else "?"
                 valueToMaybe t = if t == "" then Nothing else Just t
                 queryText = map (id *** valueToMaybe) nonEmptyParams
-            in copyByteString routeBS `mappend` qsSeparator `mappend` renderQueryText False queryText
+            in routeBldr `mappend` qsSeparator `mappend` renderQueryText False queryText
 
     -- | Determine if a request is authorized or not.
     --
@@ -192,7 +192,7 @@ class RenderRoute site => Yesod site where
              -> [(T.Text, T.Text)] -- ^ query string
              -> Builder
     joinPath _ ar pieces' qs' =
-        fromText ar `mappend` encodePath pieces qs
+        encodeUtf8Builder ar `mappend` encodePath pieces qs
       where
         pieces = if null pieces' then [""] else map addDash pieces'
         qs = map (TE.encodeUtf8 *** go) qs'
diff --git a/yesod-core/Yesod/Core/Content.hs b/yesod-core/Yesod/Core/Content.hs
index d33d87ad..8a01309a 100644
--- a/yesod-core/Yesod/Core/Content.hs
+++ b/yesod-core/Yesod/Core/Content.hs
@@ -53,20 +53,21 @@ import qualified Data.ByteString as B
 import qualified Data.ByteString.Lazy as L
 import Data.Text.Lazy (Text, pack)
 import qualified Data.Text as T
-import Blaze.ByteString.Builder (Builder, fromByteString, fromLazyByteString)
+import Data.Text.Encoding (encodeUtf8Builder)
+import qualified Data.Text.Lazy as TL
+import Data.ByteString.Builder (Builder, byteString, lazyByteString, stringUtf8)
 #if __GLASGOW_HASKELL__ < 710
 import Data.Monoid (mempty)
 #endif
 import Text.Hamlet (Html)
 import Text.Blaze.Html.Renderer.Utf8 (renderHtmlBuilder)
-import Data.Conduit (Source, Flush (Chunk), ResumableSource, mapOutput)
+import Data.Conduit (Flush (Chunk), ResumableSource, mapOutput)
 import Control.Monad (liftM)
 import Control.Monad.Trans.Resource (ResourceT)
 import Data.Conduit.Internal (ResumableSource (ResumableSource))
 import qualified Data.Conduit.Internal as CI
 
 import qualified Data.Aeson as J
-import qualified Blaze.ByteString.Builder.Char.Utf8 as Blaze
 import Data.Text.Lazy.Builder (toLazyText)
 import Yesod.Core.Types
 import Text.Lucius (Css, renderCss)
@@ -93,15 +94,15 @@ instance ToContent Content where
 instance ToContent Builder where
     toContent = flip ContentBuilder Nothing
 instance ToContent B.ByteString where
-    toContent bs = ContentBuilder (fromByteString bs) $ Just $ B.length bs
+    toContent bs = ContentBuilder (byteString bs) $ Just $ B.length bs
 instance ToContent L.ByteString where
-    toContent = flip ContentBuilder Nothing . fromLazyByteString
+    toContent = flip ContentBuilder Nothing . lazyByteString
 instance ToContent T.Text where
-    toContent = toContent . Blaze.fromText
+    toContent = toContent . encodeUtf8Builder
 instance ToContent Text where
-    toContent = toContent . Blaze.fromLazyText
+    toContent = toContent . foldMap encodeUtf8Builder . TL.toChunks
 instance ToContent String where
-    toContent = toContent . Blaze.fromString
+    toContent = toContent . stringUtf8
 instance ToContent Html where
     toContent bs = ContentBuilder (renderHtmlBuilder bs) Nothing
 instance ToContent () where
@@ -119,10 +120,10 @@ instance ToContent Javascript where
 instance ToFlushBuilder builder => ToContent (CI.Pipe () () builder () (ResourceT IO) ()) where
     toContent src = ContentSource $ CI.ConduitT (CI.mapOutput toFlushBuilder src >>=)
 
-instance ToFlushBuilder builder => ToContent (Source (ResourceT IO) builder) where
+instance ToFlushBuilder builder => ToContent (CI.ConduitT () builder (ResourceT IO) ()) where
     toContent src = ContentSource $ mapOutput toFlushBuilder src
 instance ToFlushBuilder builder => ToContent (ResumableSource (ResourceT IO) builder) where
-    toContent (ResumableSource src _) = toContent src
+    toContent (ResumableSource src) = toContent src
 
 -- | A class for all data which can be sent in a streaming response. Note that
 -- for textual data, instances must use UTF-8 encoding.
@@ -131,16 +132,16 @@ instance ToFlushBuilder builder => ToContent (ResumableSource (ResourceT IO) bui
 class ToFlushBuilder a where toFlushBuilder :: a -> Flush Builder
 instance ToFlushBuilder (Flush Builder) where toFlushBuilder = id
 instance ToFlushBuilder Builder where toFlushBuilder = Chunk
-instance ToFlushBuilder (Flush B.ByteString) where toFlushBuilder = fmap fromByteString
-instance ToFlushBuilder B.ByteString where toFlushBuilder = Chunk . fromByteString
-instance ToFlushBuilder (Flush L.ByteString) where toFlushBuilder = fmap fromLazyByteString
-instance ToFlushBuilder L.ByteString where toFlushBuilder = Chunk . fromLazyByteString
-instance ToFlushBuilder (Flush Text) where toFlushBuilder = fmap Blaze.fromLazyText
-instance ToFlushBuilder Text where toFlushBuilder = Chunk . Blaze.fromLazyText
-instance ToFlushBuilder (Flush T.Text) where toFlushBuilder = fmap Blaze.fromText
-instance ToFlushBuilder T.Text where toFlushBuilder = Chunk . Blaze.fromText
-instance ToFlushBuilder (Flush String) where toFlushBuilder = fmap Blaze.fromString
-instance ToFlushBuilder String where toFlushBuilder = Chunk . Blaze.fromString
+instance ToFlushBuilder (Flush B.ByteString) where toFlushBuilder = fmap byteString
+instance ToFlushBuilder B.ByteString where toFlushBuilder = Chunk . byteString
+instance ToFlushBuilder (Flush L.ByteString) where toFlushBuilder = fmap lazyByteString
+instance ToFlushBuilder L.ByteString where toFlushBuilder = Chunk . lazyByteString
+instance ToFlushBuilder (Flush Text) where toFlushBuilder = fmap (foldMap encodeUtf8Builder . TL.toChunks)
+instance ToFlushBuilder Text where toFlushBuilder = Chunk . foldMap encodeUtf8Builder . TL.toChunks
+instance ToFlushBuilder (Flush T.Text) where toFlushBuilder = fmap encodeUtf8Builder
+instance ToFlushBuilder T.Text where toFlushBuilder = Chunk . encodeUtf8Builder
+instance ToFlushBuilder (Flush String) where toFlushBuilder = fmap stringUtf8
+instance ToFlushBuilder String where toFlushBuilder = Chunk . stringUtf8
 instance ToFlushBuilder (Flush Html) where toFlushBuilder = fmap renderHtmlBuilder
 instance ToFlushBuilder Html where toFlushBuilder = Chunk . renderHtmlBuilder
 
diff --git a/yesod-core/Yesod/Core/Dispatch.hs b/yesod-core/Yesod/Core/Dispatch.hs
index d13a154d..e8895cee 100644
--- a/yesod-core/Yesod/Core/Dispatch.hs
+++ b/yesod-core/Yesod/Core/Dispatch.hs
@@ -53,8 +53,9 @@ import Data.Text (Text)
 import Data.Monoid (mappend)
 #endif
 import qualified Data.ByteString as S
+import qualified Data.ByteString.Lazy as BL
 import qualified Data.ByteString.Char8 as S8
-import qualified Blaze.ByteString.Builder
+import Data.ByteString.Builder (byteString, toLazyByteString)
 import Network.HTTP.Types (status301, status307)
 import Yesod.Routes.Parse
 import Yesod.Core.Types
@@ -115,7 +116,7 @@ toWaiAppYre yre req =
     sendRedirect y segments' env sendResponse =
          sendResponse $ W.responseLBS status
                 [ ("Content-Type", "text/plain")
-                , ("Location", Blaze.ByteString.Builder.toByteString dest')
+                , ("Location", BL.toStrict $ toLazyByteString dest')
                 ] "Redirecting"
       where
         -- Ensure that non-GET requests get redirected correctly. See:
@@ -129,7 +130,7 @@ toWaiAppYre yre req =
             if S.null (W.rawQueryString env)
                 then dest
                 else dest `mappend`
-                     Blaze.ByteString.Builder.fromByteString (W.rawQueryString env)
+                     byteString (W.rawQueryString env)
 
 -- | Same as 'toWaiAppPlain', but provides a default set of middlewares. This
 -- set may change with future releases, but currently covers:
diff --git a/yesod-core/Yesod/Core/Handler.hs b/yesod-core/Yesod/Core/Handler.hs
index 3395b3bd..93bee351 100644
--- a/yesod-core/Yesod/Core/Handler.hs
+++ b/yesod-core/Yesod/Core/Handler.hs
@@ -240,13 +240,13 @@ import           Web.PathPieces                (PathPiece(..))
 import           Yesod.Core.Class.Handler
 import           Yesod.Core.Types
 import           Yesod.Routes.Class            (Route)
-import           Blaze.ByteString.Builder (Builder)
+import           Data.ByteString.Builder (Builder)
 import           Safe (headMay)
 import           Data.CaseInsensitive (CI, original)
 import qualified Data.Conduit.List as CL
 import           Control.Monad.Trans.Resource  (MonadResource, InternalState, runResourceT, withInternalState, getInternalState, liftResourceT, resourceForkIO)
 import qualified System.PosixCompat.Files as PC
-import           Data.Conduit (Source, transPipe, Flush (Flush), yield, Producer, Sink)
+import           Data.Conduit (ConduitT, transPipe, Flush (Flush), yield, Void)
 import qualified Yesod.Core.TypeCache as Cache
 import qualified Data.Word8 as W8
 import qualified Data.Foldable as Fold
@@ -679,9 +679,10 @@ sendRawResponseNoConduit raw = withRunInIO $ \runInIO ->
 -- Warp).
 --
 -- @since 1.2.7
-sendRawResponse :: (MonadHandler m, MonadUnliftIO m)
-                => (Source IO S8.ByteString -> Sink S8.ByteString IO () -> m ())
-                -> m a
+sendRawResponse
+  :: (MonadHandler m, MonadUnliftIO m)
+  => (ConduitT () S8.ByteString IO () -> ConduitT S8.ByteString Void IO () -> m ())
+  -> m a
 sendRawResponse raw = withRunInIO $ \runInIO ->
     liftIO $ throwIO $ HCWai $ flip W.responseRaw fallback
     $ \src sink -> void $ runInIO $ raw (src' src) (CL.mapM_ sink)
@@ -1337,7 +1338,7 @@ provideRepType ct handler =
 -- | Stream in the raw request body without any parsing.
 --
 -- @since 1.2.0
-rawRequestBody :: MonadHandler m => Source m S.ByteString
+rawRequestBody :: MonadHandler m => ConduitT i S.ByteString m ()
 rawRequestBody = do
     req <- lift waiRequest
     let loop = do
@@ -1349,7 +1350,7 @@ rawRequestBody = do
 
 -- | Stream the data from the file. Since Yesod 1.2, this has been generalized
 -- to work in any @MonadResource@.
-fileSource :: MonadResource m => FileInfo -> Source m S.ByteString
+fileSource :: MonadResource m => FileInfo -> ConduitT () S.ByteString m ()
 fileSource = transPipe liftResourceT . fileSourceRaw
 
 -- | Provide a pure value for the response body.
@@ -1370,7 +1371,7 @@ respond ct = return . TypedContent ct . toContent
 --
 -- @since 1.2.0
 respondSource :: ContentType
-              -> Source (HandlerT site IO) (Flush Builder)
+              -> ConduitT () (Flush Builder) (HandlerT site IO) ()
               -> HandlerT site IO TypedContent
 respondSource ctype src = HandlerT $ \hd ->
     -- Note that this implementation relies on the fact that the ResourceT
@@ -1383,44 +1384,44 @@ respondSource ctype src = HandlerT $ \hd ->
 -- on most datatypes, such as @ByteString@ and @Html@.
 --
 -- @since 1.2.0
-sendChunk :: Monad m => ToFlushBuilder a => a -> Producer m (Flush Builder)
+sendChunk :: Monad m => ToFlushBuilder a => a -> ConduitT i (Flush Builder) m ()
 sendChunk = yield . toFlushBuilder
 
 -- | In a streaming response, send a flush command, causing all buffered data
 -- to be immediately sent to the client.
 --
 -- @since 1.2.0
-sendFlush :: Monad m => Producer m (Flush Builder)
+sendFlush :: Monad m => ConduitT i (Flush Builder) m ()
 sendFlush = yield Flush
 
 -- | Type-specialized version of 'sendChunk' for strict @ByteString@s.
 --
 -- @since 1.2.0
-sendChunkBS :: Monad m => S.ByteString -> Producer m (Flush Builder)
+sendChunkBS :: Monad m => S.ByteString -> ConduitT i (Flush Builder) m ()
 sendChunkBS = sendChunk
 
 -- | Type-specialized version of 'sendChunk' for lazy @ByteString@s.
 --
 -- @since 1.2.0
-sendChunkLBS :: Monad m => L.ByteString -> Producer m (Flush Builder)
+sendChunkLBS :: Monad m => L.ByteString -> ConduitT i (Flush Builder) m ()
 sendChunkLBS = sendChunk
 
 -- | Type-specialized version of 'sendChunk' for strict @Text@s.
 --
 -- @since 1.2.0
-sendChunkText :: Monad m => T.Text -> Producer m (Flush Builder)
+sendChunkText :: Monad m => T.Text -> ConduitT i (Flush Builder) m ()
 sendChunkText = sendChunk
 
 -- | Type-specialized version of 'sendChunk' for lazy @Text@s.
 --
 -- @since 1.2.0
-sendChunkLazyText :: Monad m => TL.Text -> Producer m (Flush Builder)
+sendChunkLazyText :: Monad m => TL.Text -> ConduitT i (Flush Builder) m ()
 sendChunkLazyText = sendChunk
 
 -- | Type-specialized version of 'sendChunk' for @Html@s.
 --
 -- @since 1.2.0
-sendChunkHtml :: Monad m => Html -> Producer m (Flush Builder)
+sendChunkHtml :: Monad m => Html -> ConduitT i (Flush Builder) m ()
 sendChunkHtml = sendChunk
 
 -- | Converts a child handler to a parent handler
diff --git a/yesod-core/Yesod/Core/Internal/Request.hs b/yesod-core/Yesod/Core/Internal/Request.hs
index b7e4e3ca..65201b19 100644
--- a/yesod-core/Yesod/Core/Internal/Request.hs
+++ b/yesod-core/Yesod/Core/Internal/Request.hs
@@ -33,9 +33,7 @@ import qualified Data.Set as Set
 import qualified Data.Text as T
 import Data.Text.Encoding (decodeUtf8With, decodeUtf8)
 import Data.Text.Encoding.Error (lenientDecode)
-import Data.Conduit
-import Data.Conduit.List (sourceList)
-import Data.Conduit.Binary (sourceFile, sinkFile)
+import Conduit
 import Data.Word (Word8, Word64)
 import Control.Monad.Trans.Resource (runResourceT, ResourceT)
 import Control.Exception (throwIO)
@@ -176,7 +174,7 @@ fromByteVector v =
 
 mkFileInfoLBS :: Text -> Text -> L.ByteString -> FileInfo
 mkFileInfoLBS name ct lbs =
-    FileInfo name ct (sourceList $ L.toChunks lbs) (`L.writeFile` lbs)
+    FileInfo name ct (sourceLazy lbs) (`L.writeFile` lbs)
 
 mkFileInfoFile :: Text -> Text -> FilePath -> FileInfo
 mkFileInfoFile name ct fp = FileInfo name ct (sourceFile fp) (\dst -> runResourceT $ sourceFile fp $$ sinkFile dst)
diff --git a/yesod-core/Yesod/Core/Internal/Response.hs b/yesod-core/Yesod/Core/Internal/Response.hs
index a7263b61..a4be46bd 100644
--- a/yesod-core/Yesod/Core/Internal/Response.hs
+++ b/yesod-core/Yesod/Core/Internal/Response.hs
@@ -6,6 +6,7 @@ module Yesod.Core.Internal.Response where
 import           Data.ByteString              (ByteString)
 import qualified Data.ByteString              as S
 import qualified Data.ByteString.Char8        as S8
+import qualified Data.ByteString.Lazy         as BL
 import           Data.CaseInsensitive         (CI)
 import qualified Data.CaseInsensitive         as CI
 import           Network.Wai
@@ -18,8 +19,7 @@ import           Yesod.Core.Types
 import qualified Network.HTTP.Types           as H
 import qualified Data.Text                    as T
 import           Control.Exception            (SomeException, handle)
-import           Blaze.ByteString.Builder     (fromLazyByteString,
-                                               toLazyByteString, toByteString)
+import           Data.ByteString.Builder      (lazyByteString, toLazyByteString)
 import qualified Data.ByteString.Lazy         as L
 import qualified Data.Map                     as Map
 import           Yesod.Core.Internal.Request  (tokenKey)
@@ -83,7 +83,7 @@ defaultStatus = H.mkStatus (-1) "INVALID DEFAULT STATUS"
 headerToPair :: Header
              -> (CI ByteString, ByteString)
 headerToPair (AddCookie sc) =
-    ("Set-Cookie", toByteString $ renderSetCookie sc)
+    ("Set-Cookie", BL.toStrict $ toLazyByteString $ renderSetCookie sc)
 headerToPair (DeleteCookie key path) =
     ( "Set-Cookie"
     , S.concat
@@ -100,7 +100,7 @@ evaluateContent (ContentBuilder b mlen) = handle f $ do
     let lbs = toLazyByteString b
         len = L.length lbs
         mlen' = mlen `mplus` Just (fromIntegral len)
-    len `seq` return (Right $ ContentBuilder (fromLazyByteString lbs) mlen')
+    len `seq` return (Right $ ContentBuilder (lazyByteString lbs) mlen')
   where
     f :: SomeException -> IO (Either ErrorResponse Content)
     f = return . Left . InternalError . T.pack . show
diff --git a/yesod-core/Yesod/Core/Internal/Run.hs b/yesod-core/Yesod/Core/Internal/Run.hs
index 668e8604..0989b025 100644
--- a/yesod-core/Yesod/Core/Internal/Run.hs
+++ b/yesod-core/Yesod/Core/Internal/Run.hs
@@ -14,7 +14,8 @@ import           Data.Monoid                  (Monoid, mempty)
 import           Control.Applicative          ((<$>))
 #endif
 import Yesod.Core.Internal.Response
-import           Blaze.ByteString.Builder     (toByteString)
+import           Data.ByteString.Builder      (toLazyByteString)
+import qualified Data.ByteString.Lazy         as BL
 import           Control.Exception            (fromException, evaluate)
 import qualified Control.Exception            as E
 import           Control.Monad.IO.Class       (MonadIO, liftIO)
@@ -372,7 +373,7 @@ yesodRender :: Yesod y
             -> [(Text, Text)] -- ^ url query string
             -> Text
 yesodRender y ar url params =
-    decodeUtf8With lenientDecode $ toByteString $
+    decodeUtf8With lenientDecode $ BL.toStrict $ toLazyByteString $
     fromMaybe
         (joinPath y ar ps
           $ params ++ params')
diff --git a/yesod-core/Yesod/Core/Types.hs b/yesod-core/Yesod/Core/Types.hs
index 680c13b8..2382f6a6 100644
--- a/yesod-core/Yesod/Core/Types.hs
+++ b/yesod-core/Yesod/Core/Types.hs
@@ -9,8 +9,7 @@
 {-# LANGUAGE UndecidableInstances #-}
 module Yesod.Core.Types where
 
-import qualified Blaze.ByteString.Builder           as BBuilder
-import qualified Blaze.ByteString.Builder.Char.Utf8
+import qualified Data.ByteString.Builder            as BB
 #if __GLASGOW_HASKELL__ < 710
 import           Control.Applicative                (Applicative (..))
 import           Control.Applicative                ((<$>))
@@ -25,7 +24,7 @@ import           Control.Monad.Logger               (LogLevel, LogSource,
 import           Control.Monad.Trans.Resource       (MonadResource (..), InternalState, runInternalState, MonadThrow (..), throwM, ResourceT)
 import           Data.ByteString                    (ByteString)
 import qualified Data.ByteString.Lazy               as L
-import           Data.Conduit                       (Flush, Source)
+import           Data.Conduit                       (Flush, ConduitT)
 import           Data.IORef                         (IORef, modifyIORef')
 import           Data.Map                           (Map, unionWith)
 import qualified Data.Map                           as Map
@@ -59,7 +58,6 @@ import           Control.Monad.Reader               (MonadReader (..))
 import           Data.Monoid                        ((<>))
 import Control.DeepSeq (NFData (rnf))
 import Control.DeepSeq.Generics (genericRnf)
-import Data.Conduit.Lazy (MonadActive, monadActive)
 import Yesod.Core.TypeCache (TypeMap, KeyedTypeMap)
 import Control.Monad.Logger (MonadLoggerIO (..))
 import Data.Semigroup (Semigroup)
@@ -134,13 +132,13 @@ type RequestBodyContents =
 data FileInfo = FileInfo
     { fileName        :: !Text
     , fileContentType :: !Text
-    , fileSourceRaw   :: !(Source (ResourceT IO) ByteString)
+    , fileSourceRaw   :: !(ConduitT () ByteString (ResourceT IO) ())
     , fileMove        :: !(FilePath -> IO ())
     }
 
 data FileUpload = FileUploadMemory !(NWP.BackEnd L.ByteString)
                 | FileUploadDisk !(InternalState -> NWP.BackEnd FilePath)
-                | FileUploadSource !(NWP.BackEnd (Source (ResourceT IO) ByteString))
+                | FileUploadSource !(NWP.BackEnd (ConduitT () ByteString (ResourceT IO) ()))
 
 -- | How to determine the root of the application for constructing URLs.
 --
@@ -288,8 +286,8 @@ data PageContent url = PageContent
     , pageBody  :: HtmlUrl url
     }
 
-data Content = ContentBuilder !BBuilder.Builder !(Maybe Int) -- ^ The content and optional content length.
-             | ContentSource !(Source (ResourceT IO) (Flush BBuilder.Builder))
+data Content = ContentBuilder !BB.Builder !(Maybe Int) -- ^ The content and optional content length.
+             | ContentSource !(ConduitT () (Flush BB.Builder) (ResourceT IO) ())
              | ContentFile !FilePath !(Maybe FilePart)
              | ContentDontEvaluate !Content
 
@@ -444,11 +442,6 @@ instance MonadIO m => MonadLogger (WidgetT site m) where
 instance MonadIO m => MonadLoggerIO (WidgetT site m) where
     askLoggerIO = WidgetT $ \_ hd -> return $ rheLog $ handlerEnv hd
 
-instance MonadActive m => MonadActive (WidgetT site m) where
-    monadActive = lift monadActive
-instance MonadActive m => MonadActive (HandlerT site m) where
-    monadActive = lift monadActive
-
 instance MonadTrans (HandlerT site) where
     lift = HandlerT . const
 
@@ -496,7 +489,7 @@ instance Monoid (UniqueList x) where
 instance Semigroup (UniqueList x)
 
 instance IsString Content where
-    fromString = flip ContentBuilder Nothing . Blaze.ByteString.Builder.Char.Utf8.fromString
+    fromString = flip ContentBuilder Nothing . BB.stringUtf8
 
 instance RenderRoute WaiSubsite where
     data Route WaiSubsite = WaiSubsiteRoute [Text] [(Text, Text)]
diff --git a/yesod-core/test/YesodCoreTest/CleanPath.hs b/yesod-core/test/YesodCoreTest/CleanPath.hs
index 8decc03a..b60a3156 100644
--- a/yesod-core/test/YesodCoreTest/CleanPath.hs
+++ b/yesod-core/test/YesodCoreTest/CleanPath.hs
@@ -22,7 +22,7 @@ import qualified Data.Text.Encoding as TE
 import Control.Arrow ((***))
 import Network.HTTP.Types (encodePath)
 import Data.Monoid (mappend)
-import Blaze.ByteString.Builder.Char.Utf8 (fromText)
+import Data.Text.Encoding (encodeUtf8Builder)
 
 data Subsite = Subsite
 
@@ -64,7 +64,7 @@ instance Yesod Y where
         corrected = filter (not . TS.null) s
 
     joinPath Y ar pieces' qs' =
-        fromText ar `Data.Monoid.mappend` encodePath pieces qs
+        encodeUtf8Builder ar `Data.Monoid.mappend` encodePath pieces qs
       where
         pieces = if null pieces' then [""] else pieces'
         qs = map (TE.encodeUtf8 *** go) qs'
diff --git a/yesod-core/test/YesodCoreTest/ErrorHandling.hs b/yesod-core/test/YesodCoreTest/ErrorHandling.hs
index db8dfe1c..f6fb6bb4 100644
--- a/yesod-core/test/YesodCoreTest/ErrorHandling.hs
+++ b/yesod-core/test/YesodCoreTest/ErrorHandling.hs
@@ -14,7 +14,7 @@ import qualified Data.ByteString.Lazy as L
 import qualified Data.ByteString.Char8 as S8
 import Control.Exception (SomeException, try)
 import Network.HTTP.Types (Status, mkStatus)
-import Blaze.ByteString.Builder (Builder, fromByteString, toLazyByteString)
+import Data.ByteString.Builder (Builder, toLazyByteString)
 import Data.Monoid (mconcat)
 import Data.Text (Text, pack)
 import Control.Monad (forM_)
@@ -101,7 +101,7 @@ getFileBadNameR :: Handler TypedContent
 getFileBadNameR = return $ TypedContent "ignored" $ ContentFile (error "filebadname") Nothing
 
 goodBuilderContent :: Builder
-goodBuilderContent = Data.Monoid.mconcat $ replicate 100 $ fromByteString "This is a test\n"
+goodBuilderContent = Data.Monoid.mconcat $ replicate 100 $ "This is a test\n"
 
 getGoodBuilderR :: Handler TypedContent
 getGoodBuilderR = return $ TypedContent "text/plain" $ toContent goodBuilderContent
diff --git a/yesod-core/test/YesodCoreTest/Links.hs b/yesod-core/test/YesodCoreTest/Links.hs
index f195368d..d461704d 100644
--- a/yesod-core/test/YesodCoreTest/Links.hs
+++ b/yesod-core/test/YesodCoreTest/Links.hs
@@ -13,7 +13,7 @@ import Yesod.Core
 import Network.Wai
 import Network.Wai.Test
 import Data.Text (Text)
-import Blaze.ByteString.Builder (toByteString)
+import Data.ByteString.Builder (toLazyByteString)
 
 data Y = Y
 mkYesod "Y" [parseRoutes|
@@ -86,7 +86,7 @@ case_blanks = runner $ do
     liftIO $ do
         let go r =
                 let (ps, qs) = renderRoute r
-                 in toByteString $ joinPath Y "" ps qs
+                 in toLazyByteString $ joinPath Y "" ps qs
         (go $ TextR "-") `shouldBe` "/single/--"
         (go $ TextR "") `shouldBe` "/single/-"
         (go $ TextsR ["", "-", "foo", "", "bar"]) `shouldBe` "/multi/-/--/foo/-/bar"
diff --git a/yesod-core/test/YesodCoreTest/RawResponse.hs b/yesod-core/test/YesodCoreTest/RawResponse.hs
index b55688d5..79f69900 100644
--- a/yesod-core/test/YesodCoreTest/RawResponse.hs
+++ b/yesod-core/test/YesodCoreTest/RawResponse.hs
@@ -22,7 +22,6 @@ import Control.Monad.Trans.Resource (register)
 import Data.IORef
 import Data.Streaming.Network (bindPortTCP)
 import Network.HTTP.Types (status200)
-import Blaze.ByteString.Builder (fromByteString)
 
 mkYesod "App" [parseRoutes|
 / HomeR GET
@@ -46,16 +45,16 @@ getHomeR = do
 getWaiStreamR :: Handler ()
 getWaiStreamR = sendWaiResponse $ responseStream status200 [] $ \send flush -> do
     flush
-    send $ fromByteString "hello"
+    send "hello"
     flush
-    send $ fromByteString " world"
+    send " world"
 
 getWaiAppStreamR :: Handler ()
 getWaiAppStreamR = sendWaiApplication $ \_ f -> f $ responseStream status200 [] $ \send flush -> do
     flush
-    send $ fromByteString "hello"
+    send "hello"
     flush
-    send $ fromByteString " world"
+    send " world"
 
 getFreePort :: IO Int
 getFreePort = do
diff --git a/yesod-core/yesod-core.cabal b/yesod-core/yesod-core.cabal
index 44e35973..bf61c3d6 100644
--- a/yesod-core/yesod-core.cabal
+++ b/yesod-core/yesod-core.cabal
@@ -25,12 +25,11 @@ library
                    , time                  >= 1.5
                    , wai                   >= 3.0
                    , wai-extra             >= 3.0.7
-                   , bytestring            >= 0.10
+                   , bytestring            >= 0.10.2
                    , text                  >= 0.7
                    , template-haskell
                    , path-pieces           >= 0.1.2    && < 0.3
                    , shakespeare           >= 2.0
-                   , blaze-builder         >= 0.2.1.4  && < 0.5
                    , transformers          >= 0.4
                    , mtl
                    , clientsession         >= 0.9.1    && < 0.10
@@ -61,6 +60,7 @@ library
                    , conduit-extra
                    , deepseq               >= 1.3
                    , deepseq-generics
+                   -- FIXME remove
                    , mwc-random
                    , primitive
                    , word8
@@ -187,7 +187,6 @@ test-suite tests
                   ,text
                   ,http-types
                   , random
-                  , blaze-builder
                   ,HUnit
                   ,QuickCheck >= 2 && < 3
                   ,transformers
diff --git a/yesod-static/Yesod/EmbeddedStatic/Generators.hs b/yesod-static/Yesod/EmbeddedStatic/Generators.hs
index 2d8aeab1..b5c760e1 100644
--- a/yesod-static/Yesod/EmbeddedStatic/Generators.hs
+++ b/yesod-static/Yesod/EmbeddedStatic/Generators.hs
@@ -24,9 +24,9 @@ module Yesod.EmbeddedStatic.Generators (
 
   -- * Util
   , pathToName
-  
+
   -- * Custom Generators
-  
+
   -- $example
 ) where
 
@@ -34,7 +34,6 @@ import Control.Applicative as A ((<$>), (<*>))
 import Control.Exception (try, SomeException)
 import Control.Monad (forM, when)
 import Data.Char (isDigit, isLower)
-import Data.Conduit (($$))
 import Data.Default (def)
 import Data.Maybe (isNothing)
 import Language.Haskell.TH
@@ -44,8 +43,7 @@ import System.FilePath ((</>))
 import Text.Jasmine (minifym)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Lazy as BL
-import qualified Data.Conduit.List as C
-import Data.Conduit.Binary (sourceHandle)
+import Conduit
 import qualified Data.Text as T
 import qualified System.Process as Proc
 import System.Exit (ExitCode (ExitSuccess))
@@ -208,13 +206,13 @@ compressTool f opts ct = do
                 }
     (Just hin, Just hout, _, ph) <- Proc.createProcess p
     (compressed, (), code) <- runConcurrently $ (,,)
-        A.<$> Concurrently (sourceHandle hout $$ C.consume)
+        A.<$> Concurrently (runConduit $ sourceHandle hout .| sinkLazy)
         A.<*> Concurrently (BL.hPut hin ct >> hClose hin)
         A.<*> Concurrently (Proc.waitForProcess ph)
     if code == ExitSuccess
         then do
             putStrLn $ "Compressed successfully with " ++ f
-            return $ BL.fromChunks compressed
+            return compressed
         else error $ "compressTool: compression failed with " ++ f
 
 
diff --git a/yesod-static/Yesod/Static.hs b/yesod-static/Yesod/Static.hs
index 883bf62e..fd5f8a70 100644
--- a/yesod-static/Yesod/Static.hs
+++ b/yesod-static/Yesod/Static.hs
@@ -94,10 +94,7 @@ import Data.List (foldl')
 import qualified Data.ByteString as S
 import System.PosixCompat.Files (getFileStatus, modificationTime)
 import System.Posix.Types (EpochTime)
-import Data.Conduit
-import Data.Conduit.List (sourceList, consume)
-import Data.Conduit.Binary (sourceFile)
-import qualified Data.Conduit.Text as CT
+import Conduit
 import Data.Functor.Identity (runIdentity)
 import System.FilePath ((</>), (<.>), takeDirectory)
 import qualified System.FilePath as F
@@ -425,8 +422,8 @@ base64md5File = fmap (base64 . encode) . hashFile
 base64md5 :: L.ByteString -> String
 base64md5 lbs =
             base64 $ encode
-          $ runIdentity
-          $ sourceList (L.toChunks lbs) $$ sinkHash
+          $ runConduitPure
+          $ Conduit.sourceLazy lbs .| sinkHash
   where
     encode d = ByteArray.convert (d :: Digest MD5)
 
@@ -461,8 +458,11 @@ combineStatics' :: CombineType
                 -> [Route Static] -- ^ files to combine
                 -> Q Exp
 combineStatics' combineType CombineSettings {..} routes = do
-    texts <- qRunIO $ runResourceT $ mapM_ yield fps $$ awaitForever readUTFFile =$ consume
-    ltext <- qRunIO $ preProcess $ TL.fromChunks texts
+    texts <- qRunIO $ runConduitRes
+                    $ yieldMany fps
+                   .| awaitForever readUTFFile
+                   .| sinkLazy
+    ltext <- qRunIO $ preProcess texts
     bs    <- qRunIO $ postProcess fps $ TLE.encodeUtf8 ltext
     let hash' = base64md5 bs
         suffix = csCombinedFolder </> hash' <.> extension
@@ -476,7 +476,7 @@ combineStatics' combineType CombineSettings {..} routes = do
     fps :: [FilePath]
     fps = map toFP routes
     toFP (StaticRoute pieces _) = csStaticDir </> F.joinPath (map T.unpack pieces)
-    readUTFFile fp = sourceFile fp =$= CT.decode CT.utf8
+    readUTFFile fp = sourceFile fp .| decodeUtf8C
     postProcess =
         case combineType of
             JS -> csJsPostProcess
diff --git a/yesod-static/yesod-static.cabal b/yesod-static/yesod-static.cabal
index 2a9c8506..8ddf0dbc 100644
--- a/yesod-static/yesod-static.cabal
+++ b/yesod-static/yesod-static.cabal
@@ -42,8 +42,7 @@ library
                    , file-embed            >= 0.0.4.1  && < 0.5
                    , http-types            >= 0.7
                    , unix-compat           >= 0.2
-                   , conduit               >= 0.5
-                   , conduit-extra
+                   , conduit               >= 1.3
                    , cryptonite-conduit    >= 0.1
                    , cryptonite            >= 0.11
                    , memory
@@ -124,7 +123,6 @@ test-suite tests
                    , unordered-containers
                    , async
                    , process
-                   , conduit-extra
                    , exceptions
 
     ghc-options:     -Wall -threaded
diff --git a/yesod/Yesod/Default/Util.hs b/yesod/Yesod/Default/Util.hs
index 897031b0..4b12326c 100644
--- a/yesod/Yesod/Default/Util.hs
+++ b/yesod/Yesod/Default/Util.hs
@@ -18,9 +18,7 @@ import qualified Data.ByteString.Lazy as L
 import Data.Text (Text, pack, unpack)
 import Yesod.Core -- purposely using complete import so that Haddock will see addStaticContent
 import Control.Monad (when, unless)
-import Control.Monad.Trans.Resource (runResourceT)
-import Data.Conduit (($$))
-import Data.Conduit.Binary (sourceLbs, sinkFileCautious)
+import Conduit
 import System.Directory (doesFileExist, createDirectoryIfMissing)
 import Language.Haskell.TH.Syntax
 import Text.Lucius (luciusFile, luciusFileReload)
@@ -46,8 +44,8 @@ addStaticContentExternal
 addStaticContentExternal minify hash staticDir toRoute ext' _ content = do
     liftIO $ createDirectoryIfMissing True statictmp
     exists <- liftIO $ doesFileExist fn'
-    unless exists $
-        liftIO $ runResourceT $ sourceLbs content' $$ sinkFileCautious fn'
+    unless exists $ withSinkFileCautious fn' $ \sink ->
+        runConduit $ sourceLazy content' .| sink
     return $ Just $ Right (toRoute ["tmp", pack fn], [])
   where
     fn, statictmp, fn' :: FilePath
diff --git a/yesod/yesod.cabal b/yesod/yesod.cabal
index fdde1f0e..5eb0f06e 100644
--- a/yesod/yesod.cabal
+++ b/yesod/yesod.cabal
@@ -38,8 +38,7 @@ library
                    , bytestring
                    , monad-logger
                    , fast-logger
-                   , conduit
-                   , conduit-extra             >= 1.1.14
+                   , conduit                   >= 1.3
                    , resourcet
                    , shakespeare
                    , streaming-commons