diff --git a/Data/Aeson/Transform.hs b/Data/Aeson/Transform.hs
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--- /dev/null
+++ b/Data/Aeson/Transform.hs
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+module Data.Aeson.Transform
+  (
+    -- * Example usage
+    -- $use
+
+    -- * Transformation builder
+    Builder(..)
+    -- * Executing transformation
+  , transform
+  ) where
+
+import Data.Aeson as A
+import Data.Text
+import qualified Data.Vector as Vec
+import qualified Data.HashMap.Strict as H
+
+-- | Transformations are specified by creating 'Builder' instances.
+-- Builders specify how to navigate through input JSON and construct
+-- output at various nodes in the tree.
+--
+data Builder =
+    Id
+  | At Text Builder
+  | Attr Text
+  | Attrs [Text]
+  | Map Builder
+  | Index Int Builder
+  | Obj (H.HashMap Text Builder)
+
+-- | Generates new Aeson 'Value' guided by a 'Builder'
+--
+transform :: Builder -> Value -> Value
+transform (At k b)    (A.Object o) = transform b $ o H.! k
+transform (At _ _)    _            = error "Expecting object (At)"
+transform (Index i b) (Array a)    = transform b $ a Vec.! i
+transform (Index _ _) _            = error "Expecting array (Index)"
+transform (Map b)     (Array a)    = Array $ Vec.map (transform b) a
+transform (Map _)     _            = error "Expecting array (Map)"
+transform (Attr k)    (A.Object o) = o H.! k
+transform (Attr _)    _            = error "Expecting object (Attr)"
+transform (Attrs ks)  (A.Object o) = A.Object $ H.filterWithKey (const . (`elem` ks)) o
+transform (Attrs _)   _            = error "Expecting object (Attrs)"
+transform (Obj fs)    x            = A.Object $ H.map (`transform` x) fs
+transform Id          x            = x
+
+-- $use
+--
+-- Filter unwanted attributes from an object
+--
+-- > Attrs ["nice", "good"]
+-- >
+-- > -- { bad: 3, good: 1, nice: 500, evil: -3 }
+-- > -- => { good: 1, nice: 500 }
+--
+-- Grab value
+--
+-- > Attr "foo"
+-- >
+-- > -- { foo: 2 } => 2
+--
+-- Dig deeper
+--
+-- > At "foo" $ Attr "bar"
+-- >
+-- > -- { foo: { bar: 3 }} => 3
+--
+-- Map stuff
+--
+-- > Map $ Attr "foo"
+-- >
+-- > -- [{ foo:1, foo:2 }] => [1, 2]
+--
+-- Extract indices
+--
+-- > Map $ Index 0 Id
+-- >
+-- > -- [[1,2], [3,4]] => [1, 3]
+--
+-- Create object
+--
+-- > Obj $ fromList [
+-- >     ("first", Index 0 Id)
+-- >   , ("second", Index 1 Id)
+-- >   ]
+-- >
+-- > -- ["hi", "bye"] => { first:"hi", second:"bye" }
diff --git a/Data/Aeson/Transform/Internal.hs b/Data/Aeson/Transform/Internal.hs
new file mode 100644
--- /dev/null
+++ b/Data/Aeson/Transform/Internal.hs
@@ -0,0 +1,3 @@
+module Data.Aeson.Transform.Internal
+    (
+    ) where
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright (c) 2014 Joe Nelson
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/Setup.lhs b/Setup.lhs
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--- /dev/null
+++ b/Setup.lhs
@@ -0,0 +1,3 @@
+#!/usr/bin/env runhaskell
+> import Distribution.Simple
+> main = defaultMain
diff --git a/aeson-t.cabal b/aeson-t.cabal
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--- /dev/null
+++ b/aeson-t.cabal
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+Name:                   aeson-t
+Version:                0.0.0
+Author:                 Joe Nelson <cred+github@begriffs.com>
+Maintainer:             Joe Nelson <cred+github@begriffs.com>
+Category:               Data
+License:                MIT
+License-File:           LICENSE
+Synopsis:               Transform JSON
+Description:
+  Provides a DSL to succinctly transform one JSON document to another.
+Cabal-Version:          >= 1.10
+Build-Type:             Simple
+
+Library
+  Default-Language:     Haskell2010
+  GHC-Options:          -Wall
+  Exposed-Modules:      Data.Aeson.Transform
+  Other-Modules:        Data.Aeson.Transform.Internal
+  Build-Depends:        base >= 4 && < 5
+                      , aeson
+                      , unordered-containers
+                      , text
+                      , bytestring
+                      , vector
+
+Test-Suite spec
+  Type:                 exitcode-stdio-1.0
+  Default-Language:     Haskell2010
+  Hs-Source-Dirs:       test
+  Ghc-Options:          -Wall
+  Main-Is:              Spec.hs
+  Build-Depends:        base
+                      , aeson-t
+                      , hspec2
+                      , aeson
+                      , unordered-containers
+                      , text
+                      , bytestring
+                      , vector
+                      , aeson-qq
+
+Source-Repository head
+  Type:                 git
+  Location:             git://github.com:begriffs/aeson-t.git
diff --git a/test/Spec.hs b/test/Spec.hs
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--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,1 @@
+{-# OPTIONS_GHC -F -pgmF hspec-discover #-}