diff --git a/CHANGELOG.md b/CHANGELOG.md
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+++ b/CHANGELOG.md
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+# Revision history for extism-manifest
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.
diff --git a/Extism/JSON.hs b/Extism/JSON.hs
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--- /dev/null
+++ b/Extism/JSON.hs
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+module Extism.JSON (
+  module Extism.JSON,
+  module Text.JSON
+) where
+
+import Text.JSON
+import qualified Data.ByteString as B
+import Data.ByteString.Internal (c2w, w2c)
+import qualified Data.ByteString.Base64 as B64
+import qualified Data.ByteString.Char8 as BS (unpack)
+
+data Nullable a = Null | NotNull a
+
+makeArray x = JSArray [showJSON a | a <- x]
+isNull JSNull = True
+isNull _ = False
+filterNulls obj = [(a, b) | (a, b) <- obj, not (isNull b)]
+object x = makeObj $ filterNulls x
+objectWithNulls x = makeObj x
+nonNull x = NotNull x
+null' = Null
+(.=) a b = (a, showJSON b)
+toNullable (Just x) = NotNull x
+toNullable Nothing = Null
+fromNullable (NotNull x) = Just x
+fromNullable Null = Nothing
+fromNotNull (NotNull x) = x
+fromNotNull Null = error "Value is Null"
+mapNullable f Null = Null
+mapNullable f (NotNull x) = NotNull (f x)
+
+(.?) (JSObject a) k =
+  case valFromObj k a of
+    Ok x -> NotNull x
+    Error _ -> Null
+(.?) _ _ = Null
+(.??) a k = toNullable $ lookup k a
+
+find :: JSON a => String -> JSValue -> Nullable a
+find k obj = obj .? k
+
+update :: JSON a => String -> a -> JSValue -> JSValue
+update k v (JSObject obj) = object $ (fromJSObject obj) ++ [k .= v]
+
+instance JSON a => JSON (Nullable a) where
+  showJSON (NotNull x) = showJSON x
+  showJSON Null = JSNull
+  readJSON JSNull = Ok Null
+  readJSON x = readJSON x
+
+
+newtype Base64 = Base64 B.ByteString
+
+instance JSON Base64 where
+  showJSON (Base64 bs) = showJSON (BS.unpack $ B64.encode bs)
+  readJSON (JSString s) =
+    let toByteString x = B.pack (Prelude.map c2w x) in
+    case B64.decode (toByteString (fromJSString s)) of
+    Left msg -> Error msg
+    Right d -> Ok (Base64 d)
diff --git a/Extism/Manifest.hs b/Extism/Manifest.hs
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--- /dev/null
+++ b/Extism/Manifest.hs
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+module Extism.Manifest where
+
+import Extism.JSON
+import qualified Data.ByteString as B
+import qualified Data.ByteString.Char8 as BS (unpack)
+
+-- | Memory options
+newtype Memory = Memory
+  {
+    memoryMaxPages :: Nullable Int
+  }
+
+instance JSON Memory where
+  showJSON (Memory max) =
+    object [
+      "max_pages" .= max
+    ]
+  readJSON obj =
+    let max = obj .? "max_pages" in
+    Ok (Memory max)
+
+-- | HTTP request
+data HTTPRequest = HTTPRequest
+  {
+    url :: String
+  , headers :: Nullable [(String, String)]
+  , method :: Nullable String
+  }
+
+makeKV x =
+  object [(k, showJSON v) | (k, v) <- x]
+
+requestObj (HTTPRequest url headers method) =
+  [
+    "url" .= url,
+    "headers" .= mapNullable makeKV headers,
+    "method" .= method
+  ]
+
+instance JSON HTTPRequest where
+  showJSON req =  object $ requestObj req
+  readJSON x =
+    let url = x .? "url" in
+    let headers =  x .? "headers" in
+    let method =  x .? "method" in
+    case url of
+      Null -> Error "Missing 'url' field"
+      NotNull url -> Ok (HTTPRequest url headers method)
+
+
+-- | WASM from file
+data WasmFile = WasmFile
+  {
+    filePath :: String
+  , fileName :: Nullable String
+  , fileHash :: Nullable String
+  }
+
+instance JSON WasmFile where
+  showJSON (WasmFile path name hash) =
+    object [
+      "path" .= path,
+      "name" .= name,
+      "hash" .= hash
+    ]
+  readJSON x =
+    let path = x .? "url" in
+    let name = x .? "name" in
+    let hash = x .? "hash" in
+    case path of
+      Null -> Error "Missing 'path' field"
+      NotNull path -> Ok (WasmFile path name hash)
+
+
+
+-- | WASM from raw bytes
+data WasmData = WasmData
+  {
+    dataBytes :: Base64
+  , dataName :: Nullable String
+  , dataHash :: Nullable String
+  }
+
+
+
+
+instance JSON WasmData where
+  showJSON (WasmData bytes name hash) =
+    object [
+      "data" .= bytes,
+      "name" .= name,
+      "hash" .= hash
+    ]
+  readJSON x =
+    let d = x .? "data" in
+    let name = x .? "name" in
+    let hash = x .? "hash" in
+    case d of
+      Null -> Error "Missing 'path' field"
+      NotNull d ->
+        case readJSON d of
+          Error msg -> Error msg
+          Ok d' -> Ok (WasmData d' name hash)
+
+
+-- | WASM from a URL
+data WasmURL = WasmURL
+  {
+    req :: HTTPRequest
+  , urlName :: Nullable String
+  , urlHash :: Nullable String
+  }
+
+
+instance JSON WasmURL where
+  showJSON (WasmURL req name hash) =
+    object (
+      "name" .= name :
+      "hash" .= hash :
+      requestObj req)
+  readJSON x =
+    let req = x .? "req" in
+    let name = x .? "name" in
+    let hash = x .? "hash" in
+    case fromNullable req of
+      Nothing -> Error "Missing 'req' field"
+      Just req -> Ok (WasmURL req name hash)
+
+-- | Specifies where to get WASM module data
+data Wasm = File WasmFile | Data WasmData | URL WasmURL
+
+instance JSON Wasm where
+  showJSON x =
+    case x of
+      File f -> showJSON f
+      Data d -> showJSON d
+      URL u -> showJSON u
+  readJSON x =
+    let file = (readJSON x :: Result WasmFile) in
+    case file of
+      Ok x -> Ok (File x)
+      Error _ ->
+        let data' = (readJSON x :: Result WasmData) in
+        case data' of
+        Ok x -> Ok (Data x)
+        Error _ ->
+          let url = (readJSON x :: Result WasmURL) in
+          case url of
+          Ok x -> Ok (URL x)
+          Error _ -> Error "JSON does not match any of the Wasm types"
+
+wasmFile :: String -> Wasm
+wasmFile path =
+  File WasmFile { filePath = path, fileName = null', fileHash = null'}
+
+wasmURL :: String -> String -> Wasm
+wasmURL method url =
+  let r = HTTPRequest { url = url, headers = null', method = nonNull method } in
+  URL WasmURL { req = r, urlName = null', urlHash = null' }
+
+wasmData :: B.ByteString -> Wasm
+wasmData d =
+  Data WasmData { dataBytes = Base64 d, dataName = null', dataHash = null' }
+
+withName :: Wasm -> String -> Wasm
+withName (Data d) name = Data d { dataName = nonNull name }
+withName (URL url) name =  URL url { urlName = nonNull name }
+withName (File f) name = File  f { fileName = nonNull name }
+
+
+withHash :: Wasm -> String -> Wasm
+withHash (Data d) hash = Data d { dataHash = nonNull hash }
+withHash (URL url) hash =  URL url { urlHash = nonNull hash }
+withHash (File f) hash = File  f { fileHash = nonNull hash }
+
+-- | The 'Manifest' type is used to provide WASM data and configuration to the
+-- | Extism runtime
+data Manifest = Manifest
+  {
+    wasm :: [Wasm]
+  , memory :: Nullable Memory
+  , config :: Nullable [(String, String)]
+  , allowedHosts :: Nullable [String]
+  , allowedPaths :: Nullable [(String, String)]
+  , timeout :: Nullable Int
+  }
+
+
+instance JSON Manifest where
+  showJSON (Manifest wasm memory config hosts paths timeout) =
+    let w = makeArray wasm in
+    object [
+      "wasm" .= w,
+      "memory" .= memory,
+      "config" .= mapNullable makeKV config,
+      "allowed_hosts" .= hosts,
+      "allowed_paths" .= mapNullable makeKV paths,
+      "timeout_ms" .= timeout
+    ]
+  readJSON x =
+    let wasm = x .? "wasm" in
+    let memory = x .? "memory" in
+    let config = x .? "config" in
+    let hosts = x .? "allowed_hosts" in
+    let paths = x .? "allowed_paths" in
+    let timeout = x .? "timeout_ms" in
+    case fromNullable wasm of
+      Nothing -> Error "Missing 'wasm' field"
+      Just wasm -> Ok (Manifest wasm memory config hosts paths timeout)
+
+-- | Create a new 'Manifest' from a list of 'Wasm'
+manifest :: [Wasm] -> Manifest
+manifest wasm =
+  Manifest {
+    wasm = wasm,
+    memory = null',
+    config = null',
+    allowedHosts = null',
+    allowedPaths = null',
+    timeout = null'
+  }
+
+-- | Update the config values
+withConfig :: Manifest -> [(String, String)] -> Manifest
+withConfig m config =
+  m { config = nonNull config }
+
+
+-- | Update allowed hosts for `extism_http_request`
+withHosts :: Manifest -> [String] -> Manifest
+withHosts m hosts =
+  m { allowedHosts = nonNull hosts }
+
+
+-- | Update allowed paths
+withPaths :: Manifest -> [(String, String)] -> Manifest
+withPaths m p =
+  m { allowedPaths = nonNull p }
+
+-- | Update plugin timeout (in milliseconds)
+withTimeout :: Manifest -> Int -> Manifest
+withTimeout m t =
+  m { timeout = nonNull t }
+
+toString :: (JSON a) => a -> String
+toString v =
+  encode (showJSON v)
diff --git a/extism-manifest.cabal b/extism-manifest.cabal
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+++ b/extism-manifest.cabal
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+cabal-version:      3.0
+name:               extism-manifest
+version:            0.1.0
+license:            BSD-3-Clause
+maintainer:         oss@extism.org
+author:             Extism authors
+bug-reports:        https://github.com/extism/extism
+synopsis:           Extism manifest bindings
+description:        Bindings to Extism WebAssembly manifest
+category:           Plugins, WebAssembly
+extra-source-files: CHANGELOG.md
+
+library
+    exposed-modules:    Extism.Manifest Extism.JSON
+    hs-source-dirs:     .
+    default-language:   Haskell2010
+    build-depends:
+        base              >= 4.16.1 && < 4.18.0,
+        bytestring        >= 0.11.3 && < 0.12,
+        json              >= 0.10 && < 0.11,
+        base64-bytestring >= 1.2.1 && < 1.3,