diff --git a/Data/ZoomCache/Binary.hs b/Data/ZoomCache/Binary.hs
new file mode 100644
--- /dev/null
+++ b/Data/ZoomCache/Binary.hs
@@ -0,0 +1,126 @@
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# OPTIONS -Wall #-}
+----------------------------------------------------------------------
+-- |
+-- Module      : Data.ZoomCache.Write
+-- Copyright   : Conrad Parker
+-- License     : BSD3-style (see LICENSE)
+--
+-- Maintainer  : Conrad Parker <conrad@metadecks.org>
+-- Stability   : unstable
+-- Portability : unknown
+--
+-- Blaze-builder utility functions for writing ZoomCache files.
+----------------------------------------------------------------------
+
+module Data.ZoomCache.Binary (
+    -- * Builders
+      encInt
+    , encDbl
+    , fromRational64
+    , fromGlobal
+    , fromTrackType
+    , fromDataRateType
+    , fromTrackNo
+    , fromSummary
+
+    -- * Helpers
+    , toWord64
+) where
+
+import Blaze.ByteString.Builder hiding (flush)
+import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString.Lazy.Char8 as LC
+import Data.Monoid
+import Data.Ratio
+import Data.Word
+import Unsafe.Coerce (unsafeCoerce)
+
+import Data.ZoomCache.Common
+import Data.ZoomCache.Summary
+
+----------------------------------------------------------------------
+-- Builders for local types
+
+fromGlobal :: Global -> Builder
+fromGlobal Global{..} = mconcat
+    [ fromLazyByteString globalHeader
+    , mconcat $
+        [ fromVersion version
+        , encInt noTracks
+        , fromRational64 presentationTime
+        , fromRational64 baseTime
+        ]
+    , fromLazyByteString $ LC.pack (replicate 20 '\0') -- UTCTime
+    ]
+
+fromVersion :: Version -> Builder
+fromVersion (Version vMaj vMin) = mconcat
+    [ fromInt16be . fromIntegral $ vMaj
+    , fromInt16be . fromIntegral $ vMin
+    ]
+
+fromTrackType :: TrackType -> Builder
+fromTrackType ZDouble = fromInt16be 0
+fromTrackType ZInt    = fromInt16be 1
+
+fromDataRateType :: DataRateType -> Builder
+fromDataRateType ConstantDR = fromInt16be 0
+fromDataRateType VariableDR = fromInt16be 1
+
+fromTrackNo :: TrackNo -> Builder
+fromTrackNo = fromInt32be . fromIntegral
+
+fromSummary :: Summary -> Builder
+fromSummary s@SummaryDouble{..} = mconcat [ fromSummaryHeader s, l, d]
+    where
+        d = mconcat $ map encDbl
+            [ summaryDoubleEntry
+            , summaryDoubleExit
+            , summaryDoubleMin
+            , summaryDoubleMax
+            , summaryAvg
+            , summaryRMS
+            ]
+        l = encInt . L.length . toLazyByteString $ d
+fromSummary s@SummaryInt{..} = mconcat [ fromSummaryHeader s, l, d]
+    where
+        d = mconcat $ map encInt
+            [ summaryIntEntry
+            , summaryIntExit
+            , summaryIntMin
+            , summaryIntMax
+            ] ++ map encDbl
+            [ summaryAvg
+            , summaryRMS
+            ]
+        l = encInt . L.length . toLazyByteString $ d
+
+fromSummaryHeader :: Summary -> Builder
+fromSummaryHeader s = mconcat
+    [ fromLazyByteString summaryHeader
+    , encInt . summaryTrack $ s
+    , encInt . summaryLevel $ s
+    , encInt . unTS . summaryEntryTime $ s
+    , encInt . unTS . summaryExitTime $ s
+    ]
+
+----------------------------------------------------------------------
+-- Binary data helpers
+    
+fromRational64 :: Rational -> Builder
+fromRational64 r = mconcat
+    [ fromInt64be . fromIntegral . numerator $ r
+    , fromInt64be . fromIntegral . denominator $ r
+    ]
+
+encInt :: forall a . (Integral a) => a -> Builder
+encInt = fromInt32be . fromIntegral
+
+encDbl :: Double -> Builder
+encDbl = fromWord64be . toWord64
+
+toWord64 :: Double -> Word64
+toWord64 = unsafeCoerce
+
diff --git a/zoom-cache.cabal b/zoom-cache.cabal
--- a/zoom-cache.cabal
+++ b/zoom-cache.cabal
@@ -7,7 +7,7 @@
 -- The package version. See the Haskell package versioning policy
 -- (http://www.haskell.org/haskellwiki/Package_versioning_policy) for
 -- standards guiding when and how versions should be incremented.
-Version:             0.1.0.1
+Version:             0.1.0.2
 
 -- A short (one-line) description of the package.
 Synopsis:            A streamable, seekable, zoomable cache file format
@@ -49,7 +49,8 @@
 
 Library
   -- Modules exported by the library.
-  Exposed-modules:     Data.ZoomCache.Common
+  Exposed-modules:     Data.ZoomCache.Binary
+                       Data.ZoomCache.Common
                        Data.ZoomCache.Packet
                        Data.ZoomCache.Pretty
                        Data.ZoomCache.Read