diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2020 Tom Sydney Kerckhove
+
+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/genvalidity-sydtest-aeson.cabal b/genvalidity-sydtest-aeson.cabal
new file mode 100644
--- /dev/null
+++ b/genvalidity-sydtest-aeson.cabal
@@ -0,0 +1,66 @@
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.34.2.
+--
+-- see: https://github.com/sol/hpack
+
+name:           genvalidity-sydtest-aeson
+version:        0.0.0.0
+synopsis:       Standard spec's for aeson-related instances in sydtest
+category:       Testing
+homepage:       http://cs-syd.eu
+bug-reports:    https://github.com/NorfairKing/validity/issues
+author:         Tom Sydney Kerckhove
+maintainer:     syd@cs-syd.eu
+copyright:      Copyright: (c) 2020 Tom Sydney Kerckhove
+license:        MIT
+license-file:   LICENSE
+build-type:     Simple
+
+source-repository head
+  type: git
+  location: https://github.com/NorfairKing/validity
+
+library
+  exposed-modules:
+      Test.Syd.Validity.Aeson
+  other-modules:
+      Paths_genvalidity_sydtest_aeson
+  hs-source-dirs:
+      src/
+  ghc-options: -Wall
+  build-depends:
+      QuickCheck
+    , aeson
+    , base >=4.9 && <=5
+    , bytestring
+    , deepseq
+    , genvalidity >=0.5
+    , genvalidity-sydtest
+    , sydtest
+  default-language: Haskell2010
+
+test-suite genvalidity-sydtest-aeson-test
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  other-modules:
+      Test.Syd.Validity.AesonSpec
+      Paths_genvalidity_sydtest_aeson
+  hs-source-dirs:
+      test/
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N -Wall
+  build-tool-depends:
+      sydtest-discover:sydtest-discover
+  build-depends:
+      QuickCheck
+    , aeson
+    , base >=4.9 && <=5
+    , genvalidity >=0.7
+    , genvalidity-aeson
+    , genvalidity-sydtest
+    , genvalidity-sydtest-aeson
+    , genvalidity-text
+    , sydtest
+    , text
+    , validity >=0.9
+  default-language: Haskell2010
diff --git a/src/Test/Syd/Validity/Aeson.hs b/src/Test/Syd/Validity/Aeson.hs
new file mode 100644
--- /dev/null
+++ b/src/Test/Syd/Validity/Aeson.hs
@@ -0,0 +1,148 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+
+-- | Standard test `Spec`s and raw `Property`s for `FromJSON` and `ToJSON` instances.
+--
+-- You will need @TypeApplications@ to use these.
+module Test.Syd.Validity.Aeson
+  ( jsonSpecOnValid,
+    jsonSpec,
+    jsonSpecOnArbitrary,
+    jsonSpecOnGen,
+    neverFailsToEncodeOnGen,
+    encodeAndDecodeAreInversesOnGen,
+  )
+where
+
+import Control.DeepSeq (deepseq)
+import Control.Exception (evaluate)
+import Data.Aeson (FromJSON, ToJSON)
+import qualified Data.Aeson as JSON
+import Data.GenValidity
+import Data.Typeable
+import Test.QuickCheck
+import Test.Syd
+import Test.Syd.Validity.Utils
+
+-- | Standard test spec for properties of JSON-related functions for valid values
+--
+-- Example usage:
+--
+-- > jsonSpecOnValid @Rational
+jsonSpecOnValid ::
+  forall a.
+  (Show a, Eq a, Typeable a, GenValid a, FromJSON a, ToJSON a) =>
+  Spec
+jsonSpecOnValid = jsonSpecOnGen (genValid @a) "valid" shrinkValid
+
+-- | Standard test spec for properties of JSON-related functions for unchecked values
+--
+-- Example usage:
+--
+-- > jsonSpec @Int
+jsonSpec ::
+  forall a.
+  (Show a, Eq a, Typeable a, GenUnchecked a, FromJSON a, ToJSON a) =>
+  Spec
+jsonSpec = jsonSpecOnGen (genUnchecked @a) "unchecked" shrinkUnchecked
+
+-- | Standard test spec for properties of JSON-related functions for arbitrary values
+--
+-- Example usage:
+--
+-- > jsonSpecOnArbitrary @Int
+jsonSpecOnArbitrary ::
+  forall a.
+  (Show a, Eq a, Typeable a, Arbitrary a, FromJSON a, ToJSON a) =>
+  Spec
+jsonSpecOnArbitrary = jsonSpecOnGen (arbitrary @a) "arbitrary" shrink
+
+-- | Standard test spec for properties of JSON-related functions for a given generator (and a name for that generator).
+--
+-- Example usage:
+--
+-- > jsonSpecOnGen (genListOf $ pure 'a') "sequence of 'a's"
+jsonSpecOnGen ::
+  forall a.
+  (Show a, Eq a, Typeable a, FromJSON a, ToJSON a) =>
+  Gen a ->
+  String ->
+  (a -> [a]) ->
+  Spec
+jsonSpecOnGen gen genname s =
+  parallel $ do
+    let name = nameOf @a
+    describe ("JSON " ++ name ++ " (" ++ genname ++ ")") $ do
+      describe
+        ("encode :: " ++ name ++ " -> Data.ByteString.Lazy.ByteString")
+        $ it
+          ( unwords
+              [ "never fails to encode a",
+                "\"" ++ genname,
+                name ++ "\""
+              ]
+          )
+          $ neverFailsToEncodeOnGen gen s
+      describe
+        ( "decode :: Data.ByteString.Lazy.ByteString -> Either String "
+            ++ name
+        )
+        $ it
+          ( unwords
+              [ "ensures that encode and decode are inverses for",
+                "\"" ++ genname,
+                name ++ "\"" ++ "'s"
+              ]
+          )
+          $ encodeAndDecodeAreInversesOnGen gen s
+
+-- |
+--
+-- prop> neverFailsToEncodeOnGen @Bool arbitrary shrink
+-- prop> neverFailsToEncodeOnGen @Bool genUnchecked shrinkUnchecked
+-- prop> neverFailsToEncodeOnGen @Bool genValid shrinkValid
+-- prop> neverFailsToEncodeOnGen @Int arbitrary shrink
+-- prop> neverFailsToEncodeOnGen @Int genUnchecked shrinkUnchecked
+-- prop> neverFailsToEncodeOnGen @Int genValid shrinkValid
+neverFailsToEncodeOnGen :: (Show a, ToJSON a) => Gen a -> (a -> [a]) -> Property
+neverFailsToEncodeOnGen gen s =
+  forAllShrink gen s $ \(a :: a) ->
+    evaluate (deepseq (JSON.encode a) ()) `shouldReturn` ()
+
+-- |
+--
+-- prop> encodeAndDecodeAreInversesOnGen @Bool arbitrary shrink
+-- prop> encodeAndDecodeAreInversesOnGen @Bool genUnchecked shrinkUnchecked
+-- prop> encodeAndDecodeAreInversesOnGen @Bool genValid shrinkValid
+-- prop> encodeAndDecodeAreInversesOnGen @Int arbitrary shrink
+-- prop> encodeAndDecodeAreInversesOnGen @Int genUnchecked shrinkUnchecked
+-- prop> encodeAndDecodeAreInversesOnGen @Int genValid shrinkValid
+encodeAndDecodeAreInversesOnGen ::
+  (Show a, Eq a, FromJSON a, ToJSON a) => Gen a -> (a -> [a]) -> Property
+encodeAndDecodeAreInversesOnGen gen s =
+  forAllShrink gen s $ \(a :: a) ->
+    let encoded = JSON.encode a
+        errOrDecoded = JSON.eitherDecode encoded
+     in case errOrDecoded of
+          Left err ->
+            expectationFailure $
+              unlines
+                [ "Decoding failed with error",
+                  err,
+                  "instead of decoding to",
+                  show a,
+                  "'encode' encoded it to the json",
+                  show encoded
+                ]
+          Right decoded ->
+            let ctx =
+                  unlines
+                    [ "Decoding succeeded, but the decoded value",
+                      show decoded,
+                      "differs from expected decoded value",
+                      show a,
+                      "'encode' encoded it to the json",
+                      show encoded
+                    ]
+             in context ctx $ decoded `shouldBe` a
diff --git a/test/Spec.hs b/test/Spec.hs
new file mode 100644
--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,1 @@
+{-# OPTIONS_GHC -F -pgmF sydtest-discover #-}
diff --git a/test/Test/Syd/Validity/AesonSpec.hs b/test/Test/Syd/Validity/AesonSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Test/Syd/Validity/AesonSpec.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
+module Test.Syd.Validity.AesonSpec where
+
+import Data.Aeson
+import Data.GenValidity
+import Data.GenValidity.Aeson ()
+import Data.GenValidity.Text ()
+import Data.Text (Text)
+import GHC.Generics
+import Test.Syd
+import Test.Syd.Validity.Aeson
+
+spec :: Spec
+spec = do
+  jsonSpecOnGen (genListOf $ pure 'a') "sequence of 'a's" (const [])
+  -- jsonSpec @Double DOES NOT HOLD
+  jsonSpecOnValid @Rational
+  jsonSpec @Int
+  jsonSpecOnArbitrary @Int
+  jsonSpecOnValid @ForShow
+  jsonSpecOnValid @Value
+
+-- shrinkValidSpec @Value
+
+newtype ForShow
+  = ForShow Text
+  deriving (Show, Eq, Generic)
+
+instance Validity ForShow
+
+instance GenValid ForShow where
+  genValid = genValidStructurally
+  shrinkValid = shrinkValidStructurally
+
+instance FromJSON ForShow
+
+instance ToJSON ForShow