diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for http3
 
+## 0.0.17
+
+* Providing ServerIO API
+
 ## 0.0.16
 
 * Using quic v0.2
diff --git a/Network/HTTP3/Server.hs b/Network/HTTP3/Server.hs
--- a/Network/HTTP3/Server.hs
+++ b/Network/HTTP3/Server.hs
@@ -13,14 +13,21 @@
     Hooks (..),
     defaultHooks,
     module Network.HTTP.Semantics.Server,
+
+    -- * Internal
+    runIO,
+    ServerIO (..),
 ) where
 
 import Control.Concurrent
+import Control.Concurrent.Async
+import Control.Concurrent.STM
 import Data.IORef
 import Network.HTTP.Semantics
 import Network.HTTP.Semantics.Server
 import Network.HTTP.Semantics.Server.Internal
-import Network.QUIC (Connection, Stream)
+import Network.HTTP2.Server.Internal (ServerIO (..))
+import Network.QUIC (Connection, ConnectionInfo (..), Stream, getConnectionInfo)
 import qualified Network.QUIC as QUIC
 import qualified System.TimeManager as T
 import qualified UnliftIO.Exception as E
@@ -40,16 +47,42 @@
 run conn conf server = E.bracket open close $ \ctx -> do
     tid <- forkIO $ setupUnidirectional conn conf
     addThreadId ctx tid
-    readerServer ctx server
+    readerServer ctx $ \strm ->
+        void $
+            forkFinally
+                (processRequest ctx server strm)
+                (\_ -> closeStream strm)
   where
     open = do
         ref <- newIORef IInit
         newContext conn conf (controlStream conn ref)
     close = clearContext
 
-readerServer :: Context -> Server -> IO ()
-readerServer ctx server = loop
+runIO :: Connection -> Config -> (ServerIO Stream -> IO (IO ())) -> IO ()
+runIO conn conf action = E.bracket open close $ \ctx -> do
+    tid <- forkIO $ setupUnidirectional conn conf
+    info <- getConnectionInfo conn
+    addThreadId ctx tid
+    reqq <- newTQueueIO
+    let sio =
+            ServerIO
+                { sioMySockAddr = localSockAddr info
+                , sioPeerSockAddr = remoteSockAddr info
+                , sioReadRequest = atomically $ readTQueue reqq
+                , sioWriteResponse = sendResponseIO ctx
+                }
+        put strmreq = atomically $ writeTQueue reqq strmreq
+    io <- action sio
+    concurrently_ io (readerServer ctx $ processRequestIO ctx put)
   where
+    open = do
+        ref <- newIORef IInit
+        newContext conn conf (controlStream conn ref)
+    close = clearContext
+
+readerServer :: Context -> (Stream -> IO ()) -> IO ()
+readerServer ctx action = loop
+  where
     loop = do
         accept ctx >>= process
         loop
@@ -57,8 +90,7 @@
         | QUIC.isClientInitiatedUnidirectional sid = do
             tid <- forkIO $ unidirectional ctx strm
             addThreadId ctx tid
-        | QUIC.isClientInitiatedBidirectional sid =
-            void $ forkFinally (processRequest ctx server strm) (\_ -> closeStream strm)
+        | QUIC.isClientInitiatedBidirectional sid = action strm
         | QUIC.isServerInitiatedUnidirectional sid = return () -- error
         | otherwise = return ()
       where
@@ -71,20 +103,8 @@
     mvt <- recvHeader ctx src
     case mvt of
         Nothing -> QUIC.resetStream strm H3MessageError
-        Just ht@(_, vt) -> do
-            let mMethod = getFieldValue tokenMethod vt
-                mScheme = getFieldValue tokenScheme vt
-                mAuthority = getFieldValue tokenAuthority vt
-                mPath = getFieldValue tokenPath vt
-            case (mMethod, mScheme, mAuthority, mPath) of
-                (Just "CONNECT", _, Just _, _) -> return ()
-                (Just _, Just _, Just _, Just _) -> return ()
-                _ -> QUIC.resetStream strm H3MessageError
-            -- fixme: Content-Length
-            refI <- newIORef IInit
-            refH <- newIORef Nothing
-            let readB = recvBody ctx src refI refH
-                req = Request $ InpObj ht Nothing readB refH
+        Just ht -> do
+            req <- mkRequest ctx strm src ht
             let aux = Aux th (getMySockAddr ctx) (getPeerSockAddr ctx)
             server req aux $ sendResponse ctx strm th
   where
@@ -93,9 +113,54 @@
             abort ctx QpackDecompressionFailed
         | otherwise = QUIC.resetStream strm H3MessageError
 
+processRequestIO :: Context -> ((Stream, Request) -> IO ()) -> Stream -> IO ()
+processRequestIO ctx put strm = E.handleAny reset $ do
+    src <- newSource strm
+    mvt <- recvHeader ctx src
+    case mvt of
+        Nothing -> QUIC.resetStream strm H3MessageError
+        Just ht -> do
+            req <- mkRequest ctx strm src ht
+            put (strm, req)
+  where
+    reset se
+        | Just (_ :: DecodeError) <- E.fromException se =
+            abort ctx QpackDecompressionFailed
+        | otherwise = QUIC.resetStream strm H3MessageError
+
+mkRequest
+    :: Context
+    -> Stream
+    -> Source
+    -> (TokenHeaderList, ValueTable)
+    -> IO Request
+mkRequest ctx strm src ht@(_, vt) = do
+    let mMethod = getFieldValue tokenMethod vt
+        mScheme = getFieldValue tokenScheme vt
+        mAuthority = getFieldValue tokenAuthority vt
+        mPath = getFieldValue tokenPath vt
+    case (mMethod, mScheme, mAuthority, mPath) of
+        (Just "CONNECT", _, Just _, _) -> return ()
+        (Just _, Just _, Just _, Just _) -> return ()
+        _ -> QUIC.resetStream strm H3MessageError
+    -- fixme: Content-Length
+    refI <- newIORef IInit
+    refH <- newIORef Nothing
+    let readB = recvBody ctx src refI refH
+        req = Request $ InpObj ht Nothing readB refH
+    return req
+
 sendResponse
     :: Context -> Stream -> T.Handle -> Response -> [PushPromise] -> IO ()
 sendResponse ctx strm th (Response outobj) _pp = do
     sendHeader ctx strm th $ outObjHeaders outobj
     sendBody ctx strm th outobj
     QUIC.shutdownStream strm
+
+sendResponseIO
+    :: Context -> Stream -> Response -> IO ()
+sendResponseIO ctx strm (Response outobj) = do
+    th <- registerThread ctx -- fixme
+    sendHeader ctx strm th $ outObjHeaders outobj
+    sendBody ctx strm th outobj
+    QUIC.closeStream strm
diff --git a/http3.cabal b/http3.cabal
--- a/http3.cabal
+++ b/http3.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.4
 name:               http3
-version:            0.0.16
+version:            0.0.17
 license:            BSD-3-Clause
 license-file:       LICENSE
 maintainer:         Kazu Yamamoto <kazu@iij.ad.jp>
@@ -77,6 +77,7 @@
     ghc-options:        -Wall
     build-depends:
         base >=4.9 && <5,
+        async,
         array,
         bytestring,
         case-insensitive,