diff --git a/CMakeLists.txt b/CMakeLists.txt
index 62ba80d..b04034c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -185,6 +185,11 @@ google_binary(cartographer_migrate_serialization_format
     cartographer/io/migrate_serialization_format_main.cc
 )
 
+google_binary(cartographer_pbstream_info
+  SRCS
+  cartographer/io/pbstream_info_main.cc
+)
+
 if(${BUILD_GRPC})
   google_binary(cartographer_grpc_server
     SRCS
diff --git a/cartographer/io/pbstream_info_main.cc b/cartographer/io/pbstream_info_main.cc
new file mode 100644
index 0000000..6810b99
--- /dev/null
+++ b/cartographer/io/pbstream_info_main.cc
@@ -0,0 +1,122 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "cartographer/io/proto_stream.h"
+#include "cartographer/io/proto_stream_deserializer.h"
+#include "gflags/gflags.h"
+#include "glog/logging.h"
+
+DEFINE_string(pbstream_filename, "", "Proto stream file.");
+DEFINE_bool(all_debug_strings, false,
+            "Print debug strings of all serialized data.");
+
+namespace cartographer {
+namespace mapping {
+namespace {
+
+void Run(const std::string& pbstream_filename, bool all_debug_strings) {
+  LOG(INFO) << "Reading pbstream file from '" << pbstream_filename << "'...";
+  io::ProtoStreamReader reader(pbstream_filename);
+  io::ProtoStreamDeserializer deserializer(&reader);
+  const auto header = deserializer.header();
+  LOG(INFO) << "Header: " << header.DebugString();
+  for (const proto::TrajectoryBuilderOptionsWithSensorIds& trajectory_options :
+       deserializer.all_trajectory_builder_options()
+           .options_with_sensor_ids()) {
+    LOG(INFO) << "Trajectory options: " << trajectory_options.DebugString();
+  }
+  const proto::PoseGraph pose_graph = deserializer.pose_graph();
+  for (const proto::Trajectory& trajectory : pose_graph.trajectory()) {
+    LOG(INFO) << "Trajectory id: " << trajectory.trajectory_id()
+              << " has #nodes " << trajectory.node_size() << " has #submaps "
+              << trajectory.submap_size();
+  }
+  if (all_debug_strings) {
+    LOG(INFO) << "Pose graph: " << pose_graph.DebugString();
+  }
+
+  const std::map<proto::SerializedData::DataCase, std::string>
+      data_case_to_name = {
+          {proto::SerializedData::kSubmap, "submap"},
+          {proto::SerializedData::kNode, "node"},
+          {proto::SerializedData::kTrajectoryData, "trajectory_data"},
+          {proto::SerializedData::kImuData, "imu_data"},
+          {proto::SerializedData::kOdometryData, "odometry_data"},
+          {proto::SerializedData::kFixedFramePoseData, "fixed_frame_pose_data"},
+          {proto::SerializedData::kLandmarkData, "landmark_data"},
+      };
+  // Initialize so zero counts of these are also reported.
+  std::map<std::string, int> data_counts = {
+      {"submap_2d", 0},
+      {"submap_2d_grid", 0},
+      {"submap_3d", 0},
+      {"submap_3d_high_resolution_hybrid_grid", 0},
+  };
+  proto::SerializedData proto;
+  while (deserializer.ReadNextSerializedData(&proto)) {
+    if (all_debug_strings) {
+      LOG(INFO) << "Serialized data: " << proto.DebugString();
+    }
+    auto it = data_case_to_name.find(proto.data_case());
+    if (it == data_case_to_name.end()) {
+      LOG(WARNING) << "Skipping unknown message type in stream: "
+                   << proto.GetTypeName();
+    }
+    const std::string& data_name = it->second;
+    ++data_counts[data_name];
+    if (proto.data_case() == proto::SerializedData::kSubmap) {
+      if (proto.mutable_submap()->has_submap_2d()) {
+        ++data_counts["submap_2d"];
+        if (proto.mutable_submap()->mutable_submap_2d()->has_grid()) {
+          ++data_counts["submap_2d_grid"];
+        }
+      }
+      if (proto.mutable_submap()->has_submap_3d()) {
+        ++data_counts["submap_3d"];
+        if (proto.mutable_submap()
+                ->mutable_submap_3d()
+                ->has_high_resolution_hybrid_grid()) {
+          ++data_counts["submap_3d_high_resolution_hybrid_grid"];
+        }
+      }
+    }
+  }
+
+  for (const auto& entry : data_counts) {
+    LOG(INFO) << "SerializedData package contains #" << entry.first << ": "
+              << entry.second;
+  }
+}
+
+}  // namespace
+}  // namespace mapping
+}  // namespace cartographer
+
+int main(int argc, char** argv) {
+  google::InitGoogleLogging(argv[0]);
+  FLAGS_logtostderr = true;
+  google::SetUsageMessage(
+      "\n\n"
+      "Reads a pbstream file and summarizes its contents.\n");
+  google::ParseCommandLineFlags(&argc, &argv, true);
+
+  if (FLAGS_pbstream_filename.empty()) {
+    google::ShowUsageWithFlagsRestrict(argv[0], "pbstream_info");
+    return EXIT_FAILURE;
+  }
+  ::cartographer::mapping::Run(FLAGS_pbstream_filename,
+                               FLAGS_all_debug_strings);
+}