diff --git a/api/udpa/data/orca/v1/BUILD b/api/udpa/data/orca/v1/BUILD
new file mode 100644
index 0000000000000..096ca28bac3b3
--- /dev/null
+++ b/api/udpa/data/orca/v1/BUILD
@@ -0,0 +1,16 @@
+load("@envoy_api//bazel:api_build_system.bzl", "api_go_proto_library", "api_proto_library")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_library(
+    name = "orca_load_report",
+    srcs = ["orca_load_report.proto"],
+    visibility = [
+        "//visibility:public",
+    ],
+)
+
+api_go_proto_library(
+    name = "orca_load_report",
+    proto = ":orca_load_report",
+)
diff --git a/api/udpa/data/orca/v1/orca_load_report.proto b/api/udpa/data/orca/v1/orca_load_report.proto
new file mode 100644
index 0000000000000..bed48ed2a88ed
--- /dev/null
+++ b/api/udpa/data/orca/v1/orca_load_report.proto
@@ -0,0 +1,31 @@
+syntax = "proto3";
+
+package udpa.data.orca.v1;
+
+option java_outer_classname = "OrcaLoadReportProto";
+option java_multiple_files = true;
+option java_package = "io.envoyproxy.udpa.data.orca.v1";
+option go_package = "v1";
+
+import "validate/validate.proto";
+
+// See section `ORCA load report format` of the design document in
+// :ref:`https://github.com/envoyproxy/envoy/issues/6614`.
+
+message OrcaLoadReport {
+  // CPU utilization expressed as a fraction of available CPU resources. This
+  // should be derived from a sample or measurement taken during the request.
+  double cpu_utilization = 1 [(validate.rules).double.gte = 0, (validate.rules).double.lte = 1];
+
+  // Memory utilization expressed as a fraction of available memory
+  // resources. This should be derived from a sample or measurement taken
+  // during the request.
+  double mem_utilization = 2 [(validate.rules).double.gte = 0, (validate.rules).double.lte = 1];
+
+  // Application specific requests costs. Each value may be an absolute cost (e.g.
+  // 3487 bytes of storage) or utilization associated with the request,
+  // expressed as a fraction of total resources available. Utilization
+  // metrics should be derived from a sample or measurement taken
+  // during the request.
+  map<string, double> request_cost_or_utilization = 3;
+}
\ No newline at end of file
diff --git a/api/udpa/service/orca/v1/BUILD b/api/udpa/service/orca/v1/BUILD
new file mode 100644
index 0000000000000..72543e8092216
--- /dev/null
+++ b/api/udpa/service/orca/v1/BUILD
@@ -0,0 +1,20 @@
+load("@envoy_api//bazel:api_build_system.bzl", "api_go_grpc_library", "api_proto_library_internal")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_library_internal(
+    name = "orca",
+    srcs = ["orca.proto"],
+    has_services = 1,
+    deps = [
+        "//udpa/data/orca/v1:orca_load_report",
+    ],
+)
+
+api_go_grpc_library(
+    name = "orca",
+    proto = ":orca",
+    deps = [
+        "//udpa/data/orca/v1:orca_load_report_go_proto",
+    ],
+)
diff --git a/api/udpa/service/orca/v1/orca.proto b/api/udpa/service/orca/v1/orca.proto
new file mode 100644
index 0000000000000..87871d209a4cf
--- /dev/null
+++ b/api/udpa/service/orca/v1/orca.proto
@@ -0,0 +1,38 @@
+syntax = "proto3";
+
+package udpa.service.orca.v1;
+
+option java_outer_classname = "OrcaProto";
+option java_multiple_files = true;
+option java_package = "io.envoyproxy.udpa.service.orca.v1";
+option go_package = "v1";
+
+import "udpa/data/orca/v1/orca_load_report.proto";
+
+import "google/protobuf/duration.proto";
+
+import "validate/validate.proto";
+
+// See section `Out-of-band (OOB) reporting` of the design document in
+// :ref:`https://github.com/envoyproxy/envoy/issues/6614`.
+
+// Out-of-band (OOB) load reporting service for the additional load reporting
+// agent that does not sit in the request path. Reports are periodically sampled
+// with sufficient frequency to provide temporal association with requests.
+// OOB reporting compensates the limitation of in-band reporting in revealing
+// costs for backends that do not provide a steady stream of telemetry such as
+// long running stream operations and zero QPS services. This is a server
+// streaming service, client needs to terminate current RPC and initiate
+// a new call to change backend reporting frequency.
+service OpenRcaService {
+  rpc StreamCoreMetrics(OrcaLoadReportRequest) returns (stream udpa.data.orca.v1.OrcaLoadReport);
+}
+
+message OrcaLoadReportRequest {
+  // Interval for generating Open RCA core metric responses.
+  google.protobuf.Duration report_interval = 1;
+  // Request costs to collect. If this is empty, all known requests costs tracked by
+  // the load reporting agent will be returned. This provides an opportunity for
+  // the client to selectively obtain a subset of tracked costs.
+  repeated string request_cost_names = 2;
+}
diff --git a/tools/spelling_dictionary.txt b/tools/spelling_dictionary.txt
index bd4a33889dd65..25c768b3558d7 100644
--- a/tools/spelling_dictionary.txt
+++ b/tools/spelling_dictionary.txt
@@ -160,8 +160,10 @@ NUL
 Nilsson
 OCSP
 OK
+OOB
 OOM
 OOMs
+ORCA
 OS
 OSI
 OSS
@@ -181,6 +183,7 @@ POSTs
 PREBIND
 PRNG
 PROT
+QPS
 QUIC
 RAII
 RANLUX