diff --git a/cachix-api.cabal b/cachix-api.cabal
--- a/cachix-api.cabal
+++ b/cachix-api.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.2
 name:               cachix-api
-version:            1.0.1
+version:            1.1
 synopsis:           Servant HTTP API specification for https://cachix.org
 homepage:           https://github.com/cachix/cachix#readme
 bug-reports:        https://github.com/cachix/cachix/issues
@@ -79,10 +79,12 @@
     , nix-narinfo
     , protolude
     , resourcet
+    , safe-exceptions
     , servant               >=0.14.1
     , servant-auth
     , servant-auth-swagger
     , servant-client
+    , stm-chans
     , string-conv
     , swagger2
     , text
@@ -127,4 +129,4 @@
     , transformers
     , unordered-containers
 
-  build-tool-depends: hspec-discover:hspec-discover -any
+  build-tool-depends: hspec-discover:hspec-discover
diff --git a/src/Cachix/API.hs b/src/Cachix/API.hs
--- a/src/Cachix/API.hs
+++ b/src/Cachix/API.hs
@@ -102,6 +102,7 @@
         :> "cache"
         :> Capture "name" Text
         :> "nar"
+        :> QueryParam "compression" BinaryCache.CompressionMethod
         :> StreamBody NoFraming XNixNar (ConduitT () ByteStringStreaming.ByteStringStreaming (ResourceT IO) ())
         :> Post '[JSON] NoContent,
     serveNarContent ::
diff --git a/src/Cachix/API/WebSocketSubprotocol.hs b/src/Cachix/API/WebSocketSubprotocol.hs
--- a/src/Cachix/API/WebSocketSubprotocol.hs
+++ b/src/Cachix/API/WebSocketSubprotocol.hs
@@ -1,10 +1,10 @@
-{-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DuplicateRecordFields #-}
 
 module Cachix.API.WebSocketSubprotocol where
 
 import qualified Control.Concurrent.Async as Async
-import qualified Control.Concurrent.Chan as Chan
+import qualified Control.Concurrent.STM.TMQueue as TMQueue
+import qualified Control.Exception.Safe as Safe
 import qualified Data.Aeson as Aeson
 import Data.Time (UTCTime)
 import Data.UUID (UUID)
@@ -51,27 +51,50 @@
   deriving (Show, Eq, Generic, Aeson.FromJSON, Aeson.ToJSON)
 
 parseMessage :: Aeson.FromJSON cmd => ByteString -> Either Text (Message cmd)
-parseMessage body =
-  case Aeson.eitherDecodeStrict' body of
-    Left err -> Left $ toS err
-    Right message -> Right message
+parseMessage = first toS . Aeson.eitherDecodeStrict'
 
 sendMessage :: Aeson.ToJSON cmd => WS.Connection -> Message cmd -> IO ()
 sendMessage connection cmd =
-  WS.sendTextData connection $ Aeson.encode cmd
+  WS.sendTextData connection (Aeson.encode cmd)
 
+-- | Receive and process messages in parallel.
+--
+-- Note: This will not rethrow the 'CloseRequest' exception!
+--
 -- TODO: use Async.replicateConcurrently
-recieveDataConcurrently :: WS.Connection -> (ByteString -> IO ()) -> IO ()
-recieveDataConcurrently connection m = do
-  channel <- Chan.newChan
-  Async.race_ (producer channel) (consumer channel)
+receiveDataConcurrently :: WS.Connection -> (ByteString -> IO ()) -> IO ()
+receiveDataConcurrently connection action =
+  do
+    queue <- atomically TMQueue.newTMQueue
+    Async.withAsync (consumer queue) (producer queue)
   where
-    producer channel = forever $ do
-      payload <- WS.receiveData connection
-      Chan.writeChan channel payload
-    consumer channel = forever $ do
-      payload <- Chan.readChan channel
-      m payload
+    producer queue consumerThread =
+      loop
+        `finally` closeGracefully queue consumerThread
+        `Safe.catch` closeRequest
+      where
+        loop = do
+          payload <- WS.receiveData connection
+          atomically $ TMQueue.writeTMQueue queue payload
+          loop
+
+    consumer queue = loop
+      where
+        loop = do
+          payload <- atomically $ TMQueue.readTMQueue queue
+          case payload of
+            Nothing -> return ()
+            Just msg -> action msg *> loop
+
+    -- Close the queue and wait for the consumer finish processing messages.
+    closeGracefully :: TMQueue.TMQueue a -> Async.Async () -> IO ()
+    closeGracefully queue consumerThread = do
+      atomically $ TMQueue.closeTMQueue queue
+      Async.wait consumerThread
+
+    closeRequest :: WS.ConnectionException -> IO ()
+    closeRequest (WS.CloseRequest _ _) = return ()
+    closeRequest e = throwIO e
 
 data Log = Log
   { line :: Text,
diff --git a/src/Cachix/Types/BinaryCache.hs b/src/Cachix/Types/BinaryCache.hs
--- a/src/Cachix/Types/BinaryCache.hs
+++ b/src/Cachix/Types/BinaryCache.hs
@@ -2,8 +2,9 @@
 
 import Cachix.Types.Permission (Permission)
 import Data.Aeson (FromJSON, ToJSON)
-import Data.Swagger (ToSchema)
+import Data.Swagger (ToParamSchema (..), ToSchema)
 import Protolude
+import Servant.API
 
 data BinaryCache = BinaryCache
   { name :: Text,
@@ -11,6 +12,22 @@
     isPublic :: Bool,
     publicSigningKeys :: [Text],
     githubUsername :: Text,
-    permission :: Permission
+    permission :: Permission,
+    preferredCompressionMethod :: CompressionMethod
   }
   deriving (Show, Generic, FromJSON, ToJSON, ToSchema, NFData)
+
+data CompressionMethod = XZ | ZSTD
+  deriving (Show, Read, Generic, FromJSON, ToJSON, ToSchema, NFData)
+
+instance FromHttpApiData CompressionMethod where
+  parseUrlPiece "xz" = Right XZ
+  parseUrlPiece "zst" = Right ZSTD
+  parseUrlPiece compressionMethod = Left $ "Wrong compression method: " <> compressionMethod
+
+instance ToHttpApiData CompressionMethod where
+  toUrlPiece XZ = "xz"
+  toUrlPiece ZSTD = "zst"
+
+instance ToParamSchema CompressionMethod where
+  toParamSchema _ = toParamSchema (Proxy :: Proxy Text)