diff --git a/keyserver/addons/rust-node-addon/src/identity_client/compare_users.rs b/keyserver/addons/rust-node-addon/src/identity_client/compare_users.rs
new file mode 100644
--- /dev/null
+++ b/keyserver/addons/rust-node-addon/src/identity_client/compare_users.rs
@@ -0,0 +1,36 @@
+use super::*;
+
+#[napi]
+#[instrument(skip_all)]
+async fn compare_users(
+  users: Vec<String>,
+) -> Result<HashMap<String, Vec<String>>> {
+  let channel = get_identity_service_channel().await?;
+  let token: MetadataValue<_> = IDENTITY_SERVICE_CONFIG
+    .identity_auth_token
+    .parse()
+    .map_err(|_| Error::from_status(Status::GenericFailure))?;
+  let mut identity_client =
+    IdentityServiceClient::with_interceptor(channel, |mut req: Request<()>| {
+      req.metadata_mut().insert("authorization", token.clone());
+      Ok(req)
+    });
+  let request = Request::new(CompareUsersRequest { users: users });
+
+  match identity_client.compare_users(request).await {
+    Ok(tonic_response) => {
+      let compare_users_response = tonic_response.into_inner();
+      let mut compare_result = HashMap::new();
+      compare_result.insert(
+        "usersMissingFromKeyserver".to_string(),
+        compare_users_response.users_missing_from_keyserver,
+      );
+      compare_result.insert(
+        "usersMissingFromIdentity".to_string(),
+        compare_users_response.users_missing_from_identity,
+      );
+      Ok(compare_result)
+    }
+    Err(e) => Err(Error::new(Status::GenericFailure, e.to_string())),
+  }
+}
diff --git a/keyserver/addons/rust-node-addon/src/identity_client/mod.rs b/keyserver/addons/rust-node-addon/src/identity_client/mod.rs
--- a/keyserver/addons/rust-node-addon/src/identity_client/mod.rs
+++ b/keyserver/addons/rust-node-addon/src/identity_client/mod.rs
@@ -1,3 +1,4 @@
+pub mod compare_users;
 pub mod delete_user;
 pub mod login_user;
 pub mod register_user;
@@ -21,8 +22,8 @@
   registration_request::Data::PakeRegistrationRequestAndUserId,
   registration_request::Data::PakeRegistrationUploadAndCredentialRequest,
   registration_response::Data::PakeLoginResponse as RegistrationPakeLoginResponse,
-  registration_response::Data::PakeRegistrationResponse, DeleteUserRequest,
-  LoginRequest, LoginResponse,
+  registration_response::Data::PakeRegistrationResponse, CompareUsersRequest,
+  DeleteUserRequest, LoginRequest, LoginResponse,
   PakeCredentialRequestAndUserId as PakeCredentialRequestAndUserIdStruct,
   PakeLoginRequest as PakeLoginRequestStruct,
   PakeLoginResponse as PakeLoginResponseStruct,
diff --git a/lib/types/rust-binding-types.js b/lib/types/rust-binding-types.js
--- a/lib/types/rust-binding-types.js
+++ b/lib/types/rust-binding-types.js
@@ -15,6 +15,11 @@
   publish(toDeviceId: string, payload: string): Promise<void>;
 }
 
+type UserComparisonResult = {
+  +usersMissingFromKeyserver: $ReadOnlyArray<string>,
+  +usersMissingFromIdentity: $ReadOnlyArray<string>,
+};
+
 type RustNativeBindingAPI = {
   +registerUser: (
     userId: string,
@@ -39,6 +44,9 @@
   ) => Promise<string>,
   +deleteUser: (userId: string) => Promise<boolean>,
   +updateUser: (userId: string, password: string) => Promise<string>,
+  +compareUsers: (
+    userIds: $ReadOnlyArray<string>,
+  ) => Promise<UserComparisonResult>,
   +TunnelbrokerClient: Class<TunnelbrokerClientClass>,
 };