diff --git a/application/src/main/java/net/corda/v5/application/marshalling/InteropJsonMarshallingService.java b/application/src/main/java/net/corda/v5/application/marshalling/InteropJsonMarshallingService.java
new file mode 100644
index 0000000000..4a865cdac6
--- /dev/null
+++ b/application/src/main/java/net/corda/v5/application/marshalling/InteropJsonMarshallingService.java
@@ -0,0 +1,16 @@
+package net.corda.v5.application.marshalling;
+
+import net.corda.v5.application.flows.ClientStartableFlow;
+import net.corda.v5.base.annotations.DoNotImplement;
+
+/**
+ * {@link InteropJsonMarshallingService} marshalls to and from JSON using the registered JSON mapper.
+ * <p>
+ * The platform will provide an instance of {@link InteropJsonMarshallingService} to flows via property injection.
+ * <p>
+ * Example usage:
+ * @see ClientStartableFlow
+ */
+@DoNotImplement
+public interface InteropJsonMarshallingService extends MarshallingService {
+}
diff --git a/gradle.properties b/gradle.properties
index 2943a1b91b..4c95b8c76b 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -9,7 +9,7 @@ cordaProductVersion = 5.1.0-DA
 # NOTE: update this each time this module contains a breaking change
 ## NOTE: currently this is a top level revision, so all API versions will line up, but this could be moved to
 ##   a per module property in which case module versions can change independently.
-cordaApiRevision = 38
+cordaApiRevision = 1
 
 # Main
 kotlinVersion = 1.8.21