diff --git a/marlowe-playground-client/package-lock.json b/marlowe-playground-client/package-lock.json
index 3054c8cb3..5f2f217bd 100644
--- a/marlowe-playground-client/package-lock.json
+++ b/marlowe-playground-client/package-lock.json
@@ -3758,6 +3758,11 @@
         "yallist": "^2.1.2"
       }
     },
+    "lz-string": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/lz-string/-/lz-string-1.5.0.tgz",
+      "integrity": "sha512-h5bgJWpxJNswbU7qCrV0tIKQCaS3blPDrqKWx+QxzuzL1zGUzij9XCWLrSLsJPu5t+eWA/ycetzYAO5IOMcWAQ=="
+    },
     "map-cache": {
       "version": "0.2.2",
       "resolved": "https://registry.npmjs.org/map-cache/-/map-cache-0.2.2.tgz",
diff --git a/marlowe-playground-client/package.json b/marlowe-playground-client/package.json
index 3acf71548..f927f0c8b 100644
--- a/marlowe-playground-client/package.json
+++ b/marlowe-playground-client/package.json
@@ -23,6 +23,7 @@
     "bootstrap": "^4.3.1",
     "decimal.js": "^10.0.0",
     "json-bigint": "^1.0.0",
+    "lz-string": "^1.5.0",
     "monaco-editor": "^0.22.3",
     "monaco-emacs": "^0.2.2",
     "monaco-vim": "^0.1.7",
diff --git a/marlowe-playground-client/src/MainFrame/State.purs b/marlowe-playground-client/src/MainFrame/State.purs
index 7d92fcb60..a0fd6525e 100644
--- a/marlowe-playground-client/src/MainFrame/State.purs
+++ b/marlowe-playground-client/src/MainFrame/State.purs
@@ -31,7 +31,6 @@ import Data.RawJson (RawJson(..))
 import Effect.Aff.Class (class MonadAff, liftAff)
 import Effect.Class (class MonadEffect)
 import Effect.Class.Console (log)
-import Effect.Console as Console
 import Gist (Gist, gistDescription, gistId)
 import Gists.Extra (_GistId)
 import Gists.Types (GistAction(..))
@@ -44,7 +43,6 @@ import Halogen.Monaco (KeyBindings(DefaultBindings))
 import Halogen.Monaco as Monaco
 import Halogen.Query (HalogenM)
 import Halogen.Query.Event (eventListener)
-import JSURI (encodeURIComponent)
 import Language.Marlowe.Core.V1.Semantics.Types (Contract)
 import Language.Marlowe.Extended.V1.Metadata
   ( emptyContractMetadata
@@ -127,6 +125,7 @@ import Simple.JSON (unsafeStringify)
 import StaticData (gistIdLocalStorageKey)
 import StaticData as StaticData
 import Types (WebpackBuildMode(..))
+import Web.Blob.CompressString (compressToURI)
 import Web.HTML (window)
 import Web.HTML (window) as Web
 import Web.HTML.HTMLDocument (toEventTarget)
@@ -643,15 +642,12 @@ handleAction (OpenModal modalView) = assign _showModal $ Just modalView
 handleAction CloseModal = assign _showModal Nothing
 
 handleAction (SendToRunner url contractString) = do
-  case encodeURIComponent contractString of
-    Just encodedContract -> do
-      let fullUrl = url <> "?contract=" <> encodedContract
-      liftEffect $ do
-        win <- window
-        void $ open fullUrl "_blank" "" win
-      handleAction CloseModal
-    Nothing -> do
-      liftEffect $ Console.error "Failed to encode contract string for URL."
+  let encodedContract = compressToURI contractString
+  let fullUrl = url <> "?contract=" <> encodedContract
+  liftEffect $ do
+    win <- window
+    void $ open fullUrl "_blank" "" win
+  handleAction CloseModal
 
 handleAction (OpenLoginPopup intendedAction) = do
   authRole <- liftAff openLoginPopup
diff --git a/marlowe-playground-client/src/Web/Blob/CompressString.js b/marlowe-playground-client/src/Web/Blob/CompressString.js
new file mode 100644
index 000000000..9715f42e5
--- /dev/null
+++ b/marlowe-playground-client/src/Web/Blob/CompressString.js
@@ -0,0 +1,5 @@
+import LZString from 'lz-string';
+
+export function compressToURI(originalString) {
+    return LZString.compressToEncodedURIComponent(originalString);
+}
diff --git a/marlowe-playground-client/src/Web/Blob/CompressString.purs b/marlowe-playground-client/src/Web/Blob/CompressString.purs
new file mode 100644
index 000000000..18c742712
--- /dev/null
+++ b/marlowe-playground-client/src/Web/Blob/CompressString.purs
@@ -0,0 +1,3 @@
+module Web.Blob.CompressString (compressToURI) where
+
+foreign import compressToURI :: String -> String