diff --git a/lib/jormungandr/cardano-wallet-jormungandr.cabal b/lib/jormungandr/cardano-wallet-jormungandr.cabal
index 0235e5b4168..d7ee2ed03b1 100644
--- a/lib/jormungandr/cardano-wallet-jormungandr.cabal
+++ b/lib/jormungandr/cardano-wallet-jormungandr.cabal
@@ -36,6 +36,9 @@ library
     , binary
     , bytestring
     , cardano-wallet-core
+    , servant
+    , memory
+    , http-media
     , text
     , text-class
   hs-source-dirs:
@@ -43,6 +46,7 @@ library
   exposed-modules:
       Cardano.Environment.Jormungandr
       Cardano.Wallet.Binary.Jormungandr
+      Cardano.Wallet.Network.Jormungandr.Api
       Cardano.Wallet.Compatibility.Jormungandr
       Cardano.Wallet.Transaction.Jormungandr
 
diff --git a/lib/jormungandr/src/Cardano/Wallet/Binary/Jormungandr.hs b/lib/jormungandr/src/Cardano/Wallet/Binary/Jormungandr.hs
index 2f7ea2a619e..b5a2af12964 100644
--- a/lib/jormungandr/src/Cardano/Wallet/Binary/Jormungandr.hs
+++ b/lib/jormungandr/src/Cardano/Wallet/Binary/Jormungandr.hs
@@ -25,8 +25,13 @@ module Cardano.Wallet.Binary.Jormungandr
     , LinearFee (..)
     , Milli (..)
 
+     -- * Classes
+    , FromBinary (..)
+
+
      -- * Re-export
     , runGet
+    , Get
 
     ) where
 
@@ -67,13 +72,15 @@ import Data.Quantity
 import Data.Word
     ( Word16, Word32, Word64, Word8 )
 
+import qualified Cardano.Wallet.Primitive.Types as W
+
 data BlockHeader = BlockHeader
     { version :: Word16
     , contentSize :: Word32
     , slot :: SlotId
     , chainLength :: Word32
     , contentHash :: Hash "content"
-    , parentHeaderHash :: Hash "parentHeader"
+    , parentHeaderHash :: Hash "BlockHeader"
     } deriving (Show, Eq)
 
 data Block = Block BlockHeader [Message]
@@ -364,3 +371,33 @@ whileM cond next = go
             as <- go
             return (a : as)
         else return []
+
+
+{-------------------------------------------------------------------------------
+                              Classes
+-------------------------------------------------------------------------------}
+
+class FromBinary a where
+    get :: Get a
+
+instance FromBinary Block where
+    get = getBlock
+
+instance FromBinary W.Block where
+    get = convertBlock <$> getBlock
+      where
+        convertBlock  :: Block -> W.Block
+        convertBlock (Block h msgs) =
+            W.Block (convertHeader h) (convertMessages msgs)
+
+        convertHeader :: BlockHeader -> W.BlockHeader
+        convertHeader h = W.BlockHeader (slot h) (parentHeaderHash h)
+
+        convertMessages :: [Message] -> [Tx]
+        convertMessages msgs = msgs >>= \case
+            Initial _ -> []
+            Transaction tx -> return tx
+            UnimplementedMessage _ -> []
+
+instance FromBinary a => FromBinary [a] where
+    get = whileM (not <$> isEmpty) get
diff --git a/lib/jormungandr/src/Cardano/Wallet/Network/Jormungandr/Api.hs b/lib/jormungandr/src/Cardano/Wallet/Network/Jormungandr/Api.hs
new file mode 100644
index 00000000000..fa67df32e69
--- /dev/null
+++ b/lib/jormungandr/src/Cardano/Wallet/Network/Jormungandr/Api.hs
@@ -0,0 +1,116 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE TypeOperators #-}
+
+{-#  OPTIONS_GHC -fno-warn-orphans #-} -- for content types
+
+-- |
+-- Copyright: © 2018-2019 IOHK
+-- License: MIT
+--
+-- An specification for the Jörmungandr REST API.
+module Cardano.Wallet.Network.Jormungandr.Api
+    ( Api
+    , GetBlock
+    , GetTipId
+    , GetBlockDecendantIds
+    , PostSignedTx
+    , BlockId
+    , api
+    , SignedTx
+    ) where
+
+import Prelude
+
+import Cardano.Wallet.Binary.Jormungandr
+    ( FromBinary (..), runGet )
+import Cardano.Wallet.Primitive.Types
+    ( Block, Hash (..) )
+import Data.Binary.Get
+    ( getByteString )
+import Data.ByteArray.Encoding
+    ( Base (Base16), convertFromBase, convertToBase )
+import Data.Proxy
+    ( Proxy (..) )
+import Data.Text.Encoding
+    ( decodeUtf8 )
+import Servant.API
+    ( (:<|>)
+    , (:>)
+    , Capture
+    , Get
+    , MimeUnrender (..)
+    , NoContent
+    , Post
+    , QueryParam
+    , ReqBody
+    , ToHttpApiData (..)
+    )
+import Servant.API.ContentTypes
+    ( OctetStream, PlainText )
+
+import qualified Data.ByteString.Lazy as BL
+
+
+api :: Proxy Api
+api = Proxy
+
+type Api =
+    GetBlock :<|> GetTipId :<|> GetBlockDecendantIds :<|> PostSignedTx
+
+
+-- | Retrieve a block by its id.
+type GetBlock
+    = "api"
+    :> "v0"
+    :> "block"
+    :> Capture "blockHeaderHash" BlockId
+    :> Get '[OctetStream] Block
+
+-- | Retrieve a list of 'n' block decendant ids, sorted from closest to
+-- farthest.
+--
+-- There might also exist fewer than 'n' decendants.
+type GetBlockDecendantIds
+    = "api"
+    :> "v0"
+    :> "block"
+    :> Capture "blockId" BlockId
+    :> QueryParam "count" Int
+    :> Get '[OctetStream] [BlockId]
+
+-- | Retrieve the header of the latest known block.
+type GetTipId
+    = "api"
+    :> "v0"
+    :> "tip"
+    :> Get '[PlainText] BlockId
+
+type PostSignedTx
+    = "api"
+    :> "v0"
+    :> "transaction"
+    :> ReqBody '[OctetStream] SignedTx
+    :> Post '[NoContent] NoContent
+
+-- TODO: Replace SignedTx with something real
+data SignedTx
+
+newtype BlockId = BlockId (Hash "block")
+    deriving Show
+
+instance ToHttpApiData BlockId where
+    toUrlPiece (BlockId (Hash bytes)) = decodeUtf8 $ convertToBase Base16 bytes
+
+instance FromBinary BlockId where
+    get = BlockId . Hash <$> getByteString 32
+
+instance MimeUnrender PlainText BlockId where
+    mimeUnrender _ bs =
+        BlockId . Hash <$> convertFromBase Base16 (BL.toStrict bs)
+
+-- Orphan instance
+instance FromBinary a => MimeUnrender OctetStream a where
+    mimeUnrender _ bs = Right $ runGet get bs