diff --git a/ChangeLog.md b/ChangeLog.md
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--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,5 @@
+# Changelog for composite-aeson-writeonly
+
+# (v0.1.0.0)
+
+* Add writeonly indicators `WriteOnlyJsonField`, `noRead` and `writeOnlyJsonFormat`.
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2020 Daniel Firth
+
+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/README.md b/README.md
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--- /dev/null
+++ b/README.md
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+# composite-aeson-writeonly
+
+WriteOnly indicators for composite-aeson.
diff --git a/composite-aeson-writeonly.cabal b/composite-aeson-writeonly.cabal
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--- /dev/null
+++ b/composite-aeson-writeonly.cabal
@@ -0,0 +1,34 @@
+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:           composite-aeson-writeonly
+version:        0.1.0.0
+synopsis:       WriteOnly indicators for composite-aeson.
+description:    WriteOnly indicators for composite-aeson.
+category:       Text
+author:         Daniel Firth
+maintainer:     dan.firth@homotopic.tech
+copyright:      2020 Daniel Firth
+license:        MIT
+license-file:   LICENSE
+build-type:     Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
+library
+  exposed-modules:
+      Composite.Aeson.WriteOnly
+  other-modules:
+      Paths_composite_aeson_writeonly
+  hs-source-dirs:
+      src
+  build-depends:
+      aeson
+    , aeson-better-errors
+    , base >=4.7 && <5
+    , composite-aeson
+  default-language: Haskell2010
diff --git a/src/Composite/Aeson/WriteOnly.hs b/src/Composite/Aeson/WriteOnly.hs
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--- /dev/null
+++ b/src/Composite/Aeson/WriteOnly.hs
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+{- |
+   Module     : Composite.Aeson.WriteOnly
+   License    : MIT
+   Stability  : experimental
+
+Exports WriteOnly indicators for JsonProfunctor.
+-}
+module Composite.Aeson.WriteOnly (
+  WriteOnlyJsonField
+, noRead
+, writeOnlyJsonFormat
+) where
+
+import Composite.Aeson
+import Data.Aeson
+import Data.Aeson.BetterErrors
+import Data.Functor.Identity
+
+data WriteOnlyJsonField = WriteOnlyJsonField
+  deriving Show
+
+noRead :: ParseT WriteOnlyJsonField Identity a
+noRead = throwCustomError WriteOnlyJsonField
+
+writeOnlyJsonFormat :: (a -> Value) -> JsonFormat e a
+writeOnlyJsonFormat f = jsonFormatWithoutCustomError $ JsonFormat $ JsonProfunctor f noRead