diff --git a/gate-core/src/main/groovy/com/netflix/spinnaker/gate/services/internal/KeelService.java b/gate-core/src/main/groovy/com/netflix/spinnaker/gate/services/internal/KeelService.java
index ad8451b308..85a9db9a3e 100644
--- a/gate-core/src/main/groovy/com/netflix/spinnaker/gate/services/internal/KeelService.java
+++ b/gate-core/src/main/groovy/com/netflix/spinnaker/gate/services/internal/KeelService.java
@@ -44,6 +44,9 @@ List<Map<String, Object>> getResourceEvents(
   @POST("/resources")
   Resource upsertResource(@Body Resource resource);
 
+  @POST("/resources/diff")
+  Map diffResource(@Body Resource resource);
+
   @DELETE("/resources/{name}")
   Resource deleteResource(@Path("name") String name);
 
@@ -53,6 +56,9 @@ List<Map<String, Object>> getResourceEvents(
   @POST("/delivery-configs")
   DeliveryConfig upsertManifest(@Body DeliveryConfig manifest);
 
+  @POST("/delivery-configs/diff")
+  Map diffManifest(@Body DeliveryConfig manifest);
+
   @GET("/application/{application}")
   Map getApplicationDetails(
       @Path("application") String application, @Query("includeDetails") Boolean includeDetails);
diff --git a/gate-web/src/main/groovy/com/netflix/spinnaker/gate/controllers/ManagedController.java b/gate-web/src/main/groovy/com/netflix/spinnaker/gate/controllers/ManagedController.java
index 82958d7e67..0f7e4fe077 100644
--- a/gate-web/src/main/groovy/com/netflix/spinnaker/gate/controllers/ManagedController.java
+++ b/gate-web/src/main/groovy/com/netflix/spinnaker/gate/controllers/ManagedController.java
@@ -62,6 +62,12 @@ Resource upsertResource(@RequestBody Resource resource) {
     return keelService.upsertResource(resource);
   }
 
+  @ApiOperation(value = "Ad-hoc validate and diff a resource", response = Resource.class)
+  @RequestMapping(value = "/resources/diff", method = POST)
+  Map diffResource(@RequestBody Resource resource) {
+    return keelService.diffResource(resource);
+  }
+
   @ApiOperation(value = "Delete a resource", response = Resource.class)
   @RequestMapping(value = "/resources/{name}", method = DELETE)
   Resource deleteResource(@PathVariable("name") String name) {
@@ -82,6 +88,14 @@ DeliveryConfig upsertManifest(@RequestBody DeliveryConfig manifest) {
     return keelService.upsertManifest(manifest);
   }
 
+  @ApiOperation(
+      value = "Ad-hoc validate and diff a config manifest",
+      response = DeliveryConfig.class)
+  @RequestMapping(value = "/delivery-configs", method = POST)
+  Map diffManifest(@RequestBody DeliveryConfig manifest) {
+    return keelService.diffManifest(manifest);
+  }
+
   @ApiOperation(value = "Get managed details about an application", response = Map.class)
   @RequestMapping(value = "/application/{application}", method = GET)
   Map getApplicationDetails(