diff --git a/.gitmodules b/.gitmodules
index 27ff39f0..e2c0733d 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -10,3 +10,6 @@
 [submodule "third_party/loguru"]
 	path = third_party/loguru
 	url = https://github.com/emilk/loguru
+[submodule "third_party/msgpack-c"]
+	path = third_party/msgpack-c
+	url = https://github.com/msgpack/msgpack-c
diff --git a/src/cache_manager.cc b/src/cache_manager.cc
index 9060482c..cc0e0c27 100644
--- a/src/cache_manager.cc
+++ b/src/cache_manager.cc
@@ -27,17 +27,27 @@ std::string GetCachedBaseFileName(Config* config,
   return config->cacheDirectory + cache_file;
 }
 
+std::string GetCacheFileName(Config* config, const std::string& base) {
+  switch (config->cacheFormat) {
+    case SerializeFormat::Json:
+      return base + "json";
+    case SerializeFormat::MessagePack:
+      return base + "mpack";
+  }
+}
+
 std::unique_ptr<IndexFile> LoadCachedIndex(Config* config,
                                            const std::string& filename) {
   if (!config->enableCacheRead)
     return nullptr;
 
-  optional<std::string> file_content =
-      ReadContent(GetCachedBaseFileName(config, filename) + ".json");
+  optional<std::string> file_content = ReadContent(
+      GetCacheFileName(config, GetCachedBaseFileName(config, filename)));
   if (!file_content)
     return nullptr;
 
-  return Deserialize(filename, *file_content, IndexFile::kCurrentVersion);
+  return Deserialize(config->cacheFormat, filename, *file_content,
+                     IndexFile::kCurrentVersion);
 }
 
 // Manages loading caches from file paths for the indexer process.
@@ -132,5 +142,5 @@ void WriteToCache(Config* config, IndexFile& file) {
   }
 
   std::string indexed_content = Serialize(file);
-  WriteToFile(cache_basename + ".json", indexed_content);
+  WriteToFile(GetCacheFileName(config, cache_basename), indexed_content);
 }
diff --git a/src/config.h b/src/config.h
index 7835e651..1ef56944 100644
--- a/src/config.h
+++ b/src/config.h
@@ -11,6 +11,8 @@ struct Config {
   std::string compilationDatabaseDirectory;
   // Cache directory for indexed files.
   std::string cacheDirectory;
+  // Cache serialization format
+  SerializeFormat cacheFormat = SerializeFormat::Json;
   // Value to use for clang -resource-dir if not present in
   // compile_commands.json.
   std::string resourceDirectory;
diff --git a/src/serializer.cc b/src/serializer.cc
index 36da86a8..3b5c824b 100644
--- a/src/serializer.cc
+++ b/src/serializer.cc
@@ -2,6 +2,7 @@
 
 // TODO Move Json* to serializers/json.cc
 #include "serializers/json.h"
+//#include "serializers/msgpack.h"
 
 #include "indexer.h"
 
@@ -208,7 +209,8 @@ std::string Serialize(IndexFile& file) {
   return output.GetString();
 }
 
-std::unique_ptr<IndexFile> Deserialize(std::string path,
+std::unique_ptr<IndexFile> Deserialize(SerializeFormat format,
+                                       std::string path,
                                        std::string serialized,
                                        optional<int> expected_version) {
   rapidjson::Document reader;
@@ -226,6 +228,8 @@ std::unique_ptr<IndexFile> Deserialize(std::string path,
     }
   }
 
+  // TODO msgpack
+  (void)format;
   auto file = MakeUnique<IndexFile>(path);
   JsonReader json_reader{&reader};
   Reflect(json_reader, *file);
diff --git a/src/serializer.h b/src/serializer.h
index 2edaa809..b79055b5 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -8,6 +8,8 @@
 #include <string>
 #include <vector>
 
+enum class SerializeFormat { Json, MessagePack };
+
 class Reader {
  public:
   virtual ~Reader() {}
@@ -236,7 +238,8 @@ void ReflectMember(Reader& visitor, const char* name, T& value) {
 }
 
 std::string Serialize(IndexFile& file);
-std::unique_ptr<IndexFile> Deserialize(std::string path,
+std::unique_ptr<IndexFile> Deserialize(SerializeFormat format,
+                                       std::string path,
                                        std::string serialized,
                                        optional<int> expected_version);
 
diff --git a/src/test.cc b/src/test.cc
index 7ea0d898..23a5d5a8 100644
--- a/src/test.cc
+++ b/src/test.cc
@@ -76,7 +76,8 @@ void DiffDocuments(std::string path,
 void VerifySerializeToFrom(IndexFile* file) {
   std::string expected = file->ToString();
   std::unique_ptr<IndexFile> result =
-      Deserialize("--.cc", Serialize(*file), nullopt /*expected_version*/);
+      Deserialize(SerializeFormat::Json, "--.cc", Serialize(*file),
+                  nullopt /*expected_version*/);
   std::string actual = result->ToString();
   if (expected != actual) {
     std::cerr << "Serialization failure" << std::endl;
diff --git a/third_party/msgpack-c b/third_party/msgpack-c
new file mode 160000
index 00000000..208595b2
--- /dev/null
+++ b/third_party/msgpack-c
@@ -0,0 +1 @@
+Subproject commit 208595b2620cf6260ce3d6d4cf8543f13b206449
diff --git a/wscript b/wscript
index 90a48fee..0a550e6d 100644
--- a/wscript
+++ b/wscript
@@ -362,6 +362,7 @@ def build(bld):
         'third_party/',
         'third_party/doctest/',
         'third_party/loguru/',
+        'third_party/msgpack-c/include',
         'third_party/rapidjson/include/',
         'third_party/sparsepp/'] +
         (['libclang'] if bld.env['use_clang_cxx'] else []),