diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,6 @@
+# Changelog
+
+## 0.1.0.0
+
+- Initial release
+- `Hsrs.Runtime` module with `fromBorshBuffer`, `withBorshArg`, and re-exports from `Codec.Borsh`
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Marko Vejnovic
+
+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.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/hsrs.cabal b/hsrs.cabal
new file mode 100644
--- /dev/null
+++ b/hsrs.cabal
@@ -0,0 +1,37 @@
+cabal-version: 2.4
+name:          hsrs
+version:       0.1.0.0
+synopsis:      Runtime support for hsrs-generated Haskell FFI bindings
+description:
+  Provides the Haskell-side runtime needed by code generated
+  by hsrs-codegen, including Borsh serialization utilities for
+  FFI data transfer. Users of hsrs-generated bindings only need
+  to add @hsrs@ to their @build-depends@ — the @borsh@ package
+  is pulled in transitively.
+
+license:       MIT
+license-file:  LICENSE
+author:        Marko Vejnovic
+maintainer:    marko@mesa.dev
+homepage:      https://github.com/harmont-dev/hsrs
+bug-reports:   https://github.com/harmont-dev/hsrs/issues
+category:      FFI, Foreign
+build-type:    Simple
+tested-with:   GHC == 9.6.7, GHC == 9.8.4, GHC == 9.10.1
+extra-doc-files: CHANGELOG.md
+
+source-repository head
+  type:     git
+  location: https://github.com/harmont-dev/hsrs
+  subdir:   hsrs-haskell
+
+library
+  exposed-modules: Hsrs.Runtime
+  build-depends:
+      base        >= 4.16 && < 5
+    , borsh       >= 0.3  && < 0.4
+    , bytestring  >= 0.11 && < 0.13
+    , text        >= 2.0  && < 2.3
+  hs-source-dirs: src
+  default-language: Haskell2010
+  ghc-options: -Wall
diff --git a/src/Hsrs/Runtime.hs b/src/Hsrs/Runtime.hs
new file mode 100644
--- /dev/null
+++ b/src/Hsrs/Runtime.hs
@@ -0,0 +1,52 @@
+module Hsrs.Runtime
+  ( -- * Borsh buffer FFI
+    BorshBufferRaw
+  , fromBorshBuffer
+    -- * Borsh argument marshalling
+  , withBorshArg
+    -- * Exceptions
+  , HsrsDeserialiseError(..)
+    -- * Re-exports from Codec.Borsh
+  , BorshSize
+  , ToBorsh
+  , FromBorsh
+  , AsStruct
+  , serialiseBorsh
+  , deserialiseBorsh
+    -- * Re-exports for generated code
+  , Text
+  ) where
+
+import Codec.Borsh (AsStruct, BorshSize, FromBorsh, ToBorsh, deserialiseBorsh, serialiseBorsh)
+import Control.Exception (Exception, throwIO)
+import Data.Text (Text)
+import Data.ByteString (packCStringLen, useAsCStringLen)
+import Data.Word (Word8, Word64)
+import Foreign (FinalizerPtr, Ptr, castPtr, newForeignPtr, withForeignPtr)
+
+data BorshBufferRaw
+
+foreign import ccall "hsrs_borsh_len"  c_hsrsBorshLen  :: Ptr BorshBufferRaw -> IO Word64
+foreign import ccall "hsrs_borsh_ptr"  c_hsrsBorshPtr  :: Ptr BorshBufferRaw -> IO (Ptr Word8)
+foreign import ccall "&hsrs_borsh_free" c_hsrsBorshFree :: FinalizerPtr BorshBufferRaw
+
+newtype HsrsDeserialiseError = HsrsDeserialiseError String
+  deriving (Show)
+
+instance Exception HsrsDeserialiseError
+
+fromBorshBuffer :: FromBorsh a => Ptr BorshBufferRaw -> IO a
+fromBorshBuffer bufPtr = do
+  fp <- newForeignPtr c_hsrsBorshFree bufPtr
+  withForeignPtr fp $ \p -> do
+    len <- c_hsrsBorshLen p
+    dataPtr <- c_hsrsBorshPtr p
+    bs <- packCStringLen (castPtr dataPtr, fromIntegral len)
+    case deserialiseBorsh bs of
+      Left err -> throwIO (HsrsDeserialiseError (show err))
+      Right val -> pure val
+
+withBorshArg :: ToBorsh a => a -> (Ptr Word8 -> Word64 -> IO b) -> IO b
+withBorshArg val f =
+  useAsCStringLen (serialiseBorsh val) $ \(ptr, len) ->
+    f (castPtr ptr) (fromIntegral len)