diff --git a/registry-aeson.cabal b/registry-aeson.cabal
--- a/registry-aeson.cabal
+++ b/registry-aeson.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           registry-aeson
-version:        0.2.3.2
+version:        0.2.3.3
 synopsis:       Aeson encoders / decoders
 description:    This library provides encoders / decoders which can be easily customized for the Aeson format.
 category:       Data
diff --git a/src/Data/Registry/Aeson/Decoder.hs b/src/Data/Registry/Aeson/Decoder.hs
--- a/src/Data/Registry/Aeson/Decoder.hs
+++ b/src/Data/Registry/Aeson/Decoder.hs
@@ -17,14 +17,15 @@
 where
 
 import Data.Aeson
-import Data.Map qualified as M
 import Data.Aeson.Key qualified as K
 import Data.Aeson.KeyMap qualified as KM
 import Data.ByteString.Lazy qualified as BL
 import Data.List ((\\))
+import Data.Map qualified as M
 import Data.Registry
 import Data.Registry.Aeson.TH.Decoder
 import Data.Registry.Aeson.TH.ThOptions
+import Data.Set qualified as S
 import Data.Text qualified as T
 import Data.Text.Encoding qualified as T
 import Data.Vector qualified as Vector
@@ -126,6 +127,15 @@
 tripleOfDecoder (Decoder a) (Decoder b) (Decoder c) = Decoder $ \case
   Array [oa, ob, oc] -> (,,) <$> a oa <*> b ob <*> c oc
   _ -> Left . toS $ "not a triple of " <> showType @a <> "," <> showType @b <> "," <> showType @c
+
+-- | Add a Decoder (Set a)
+decodeSetOf :: forall a. (Typeable a, Ord a) => Typed (Decoder a -> Decoder (Set a))
+decodeSetOf = fun (setOfDecoder @a)
+
+setOfDecoder :: forall a. (Typeable a, Ord a) => Decoder a -> Decoder (Set a)
+setOfDecoder (Decoder a) = Decoder $ \case
+  Array vs -> S.fromList <$> for (toList vs) a
+  _ -> Left . toS $ "not a set of " <> showType @a
 
 -- | Add a Decoder [a] to a registry of decoders
 --   usage: decoders = decodeListOf @a <: otherDecoders
diff --git a/src/Data/Registry/Aeson/Encoder.hs b/src/Data/Registry/Aeson/Encoder.hs
--- a/src/Data/Registry/Aeson/Encoder.hs
+++ b/src/Data/Registry/Aeson/Encoder.hs
@@ -25,6 +25,7 @@
 import Data.Registry
 import Data.Registry.Aeson.TH.Encoder
 import Data.Registry.Aeson.TH.ThOptions
+import Data.Set qualified as S
 import Data.Vector qualified as V
 import Protolude hiding (Type, list)
 import Prelude (String)
@@ -101,6 +102,15 @@
   Encoder $ \(a, b, c) -> do
     let (ls1, ls2) = unzip [ea a, eb b, ec c]
     (array ls1, list identity ls2)
+
+-- | Create an Encoder for a Set a
+encodeSetOf :: forall a. (Typeable a) => Typed (Encoder a -> Encoder (Set a))
+encodeSetOf = fun (setOfEncoder @a)
+
+setOfEncoder :: Encoder a -> Encoder (Set a)
+setOfEncoder (Encoder ea) = Encoder $ \as -> do
+  let (ls1, ls2) = unzip (ea <$> S.toList as)
+  (array ls1, list identity ls2)
 
 -- | Create an Encoder for a list [a]
 encodeListOf :: forall a. (Typeable a) => Typed (Encoder a -> Encoder [a])