diff --git a/autotest/CMakeLists.txt b/autotest/CMakeLists.txt
index 7d23b94..f715de3 100644
--- a/autotest/CMakeLists.txt
+++ b/autotest/CMakeLists.txt
@@ -7,7 +7,7 @@ set(AT_SRCS
 set(AT_TARGET_NAME webcc_autotest)
 
 # Common libraries to link.
-set(AT_LIBS webcc ${Boost_LIBRARIES} "${CMAKE_THREAD_LIBS_INIT}")
+set(AT_LIBS webcc jsoncpp gtest ${Boost_LIBRARIES} "${CMAKE_THREAD_LIBS_INIT}")
 
 if(WEBCC_ENABLE_SSL)
     set(AT_LIBS ${AT_LIBS} ${OPENSSL_LIBRARIES})
@@ -31,4 +31,4 @@ if(UNIX)
 endif()
 
 add_executable(${AT_TARGET_NAME} ${AT_SRCS})
-target_link_libraries(${AT_TARGET_NAME} webcc jsoncpp gtest ${AT_LIBS})
+target_link_libraries(${AT_TARGET_NAME} ${AT_LIBS})
diff --git a/examples/file_upload_client.cc b/examples/file_upload_client.cc
index 819f1f2..8f09b87 100644
--- a/examples/file_upload_client.cc
+++ b/examples/file_upload_client.cc
@@ -50,15 +50,13 @@ int main(int argc, char* argv[]) {
   webcc::ClientSession session;
 
   try {
-    //auto r = session.PostFile(url, "file", upload_dir / "remember.txt");
-
     auto r = session.Request(webcc::RequestBuilder{}.Post().
                              Url(url).
                              File("file", upload_dir / "remember.txt").
                              Form("json", "{}", "application/json")
                              ());
 
-    //std::cout << r->content() << std::endl;
+    std::cout << r->status() << std::endl;
 
   } catch (const webcc::Exception& e) {
     std::cout << "Exception: " << e.what() << std::endl;
diff --git a/examples/file_upload_server.cc b/examples/file_upload_server.cc
index 1e93b7d..f62cb10 100644
--- a/examples/file_upload_server.cc
+++ b/examples/file_upload_server.cc
@@ -10,7 +10,7 @@
 class FileUploadService : public webcc::RestService {
 public:
   void Handle(const webcc::RestRequest& request,
-              webcc::RestResponse* response) final {
+              webcc::RestResponse* response) override {
     if (request.http->method() == "POST") {
       std::cout << "files: " << request.http->form_parts().size() << std::endl;
 
diff --git a/examples/rest_book_server.cc b/examples/rest_book_server.cc
index 701bee9..bed4a0f 100644
--- a/examples/rest_book_server.cc
+++ b/examples/rest_book_server.cc
@@ -42,11 +42,11 @@ public:
 
 protected:
   // Get a list of books based on query parameters.
-  void Get(const webcc::UrlQuery& query, webcc::RestResponse* response) final;
+  void Get(const webcc::UrlQuery& query, webcc::RestResponse* response) override;
 
   // Create a new book.
   void Post(const std::string& request_content,
-            webcc::RestResponse* response) final;
+            webcc::RestResponse* response) override;
 
 private:
   // Sleep some seconds before send back the response.
@@ -68,16 +68,16 @@ protected:
   // Get the detailed information of a book.
   void Get(const webcc::UrlMatches& url_matches,
            const webcc::UrlQuery& query,
-           webcc::RestResponse* response) final;
+           webcc::RestResponse* response) override;
 
   // Update a book.
   void Put(const webcc::UrlMatches& url_matches,
            const std::string& request_content,
-           webcc::RestResponse* response) final;
+           webcc::RestResponse* response) override;
 
   // Delete a book.
   void Delete(const webcc::UrlMatches& url_matches,
-              webcc::RestResponse* response) final;
+              webcc::RestResponse* response) override;
 
 private:
   // Sleep some seconds before send back the response.
diff --git a/unittest/CMakeLists.txt b/unittest/CMakeLists.txt
index 80110f3..fb4db64 100644
--- a/unittest/CMakeLists.txt
+++ b/unittest/CMakeLists.txt
@@ -10,7 +10,7 @@ set(UT_SRCS
 set(UT_TARGET_NAME webcc_unittest)
 
 # Common libraries to link.
-set(UT_LIBS webcc ${Boost_LIBRARIES} "${CMAKE_THREAD_LIBS_INIT}")
+set(UT_LIBS webcc gtest ${Boost_LIBRARIES} "${CMAKE_THREAD_LIBS_INIT}")
 
 if(WEBCC_ENABLE_SSL)
     set(UT_LIBS ${UT_LIBS} ${OPENSSL_LIBRARIES})
@@ -34,6 +34,6 @@ if(UNIX)
 endif()
 
 add_executable(${UT_TARGET_NAME} ${UT_SRCS})
-target_link_libraries(${UT_TARGET_NAME} webcc gtest ${UT_LIBS})
+target_link_libraries(${UT_TARGET_NAME} ${UT_LIBS})
 
 add_test(${UT_TARGET_NAME} ${UT_TARGET_NAME})
diff --git a/unittest/rest_service_manager_unittest.cc b/unittest/rest_service_manager_unittest.cc
index f863e78..6d657d2 100644
--- a/unittest/rest_service_manager_unittest.cc
+++ b/unittest/rest_service_manager_unittest.cc
@@ -7,7 +7,7 @@
 class MyRestService : public webcc::RestService {
 public:
   void Handle(const webcc::RestRequest& request,
-              webcc::RestResponse* response) final {
+              webcc::RestResponse* response) override {
     response->status = webcc::Status::kOK;
   }
 };
diff --git a/webcc/client_session.cc b/webcc/client_session.cc
index b1fc564..bb65d5a 100644
--- a/webcc/client_session.cc
+++ b/webcc/client_session.cc
@@ -121,36 +121,6 @@ ResponsePtr ClientSession::Patch(const std::string& url, std::string&& data,
   return Request(builder());
 }
 
-ResponsePtr ClientSession::PostFile(const std::string& url,
-                                    const std::string& name, const Path& path,
-                                    const std::vector<std::string>& headers) {
-  RequestBuilder builder;
-  builder.Post().Url(url);
-
-  SetHeaders(headers, &builder);
-
-  builder.File(name, path);
-
-  return Request(builder());
-}
-
-ResponsePtr ClientSession::PostFiles(const std::string& url,
-                                     const std::map<std::string, Path>& paths,
-                                     const std::vector<std::string>& headers) {
-  assert(!paths.empty());
-
-  RequestBuilder builder;
-  builder.Post().Url(url);
-
-  SetHeaders(headers, &builder);
-
-  for (auto& pair : paths) {
-    builder.File(pair.first, pair.second);
-  }
-
-  return Request(builder());
-}
-
 void ClientSession::InitHeaders() {
   using namespace headers;
 
diff --git a/webcc/client_session.h b/webcc/client_session.h
index b8b6fcd..15e76fd 100644
--- a/webcc/client_session.h
+++ b/webcc/client_session.h
@@ -79,16 +79,6 @@ public:
   ResponsePtr Patch(const std::string& url, std::string&& data, bool json,
                     const std::vector<std::string>& headers = {});
 
-  // Post a file.
-  ResponsePtr PostFile(const std::string& url, const std::string& name,
-                       const Path& path,
-                       const std::vector<std::string>& headers = {});
-
-  // Post multiple files.
-  ResponsePtr PostFiles(const std::string& url,
-                        const std::map<std::string, Path>& paths,
-                        const std::vector<std::string>& headers = {});
-
 private:
   void InitHeaders();
 
diff --git a/webcc/common.cc b/webcc/common.cc
index 31544a4..3c79922 100644
--- a/webcc/common.cc
+++ b/webcc/common.cc
@@ -6,6 +6,7 @@
 #include "boost/filesystem/fstream.hpp"
 
 #include "webcc/logger.h"
+#include "webcc/utility.h"
 
 namespace bfs = boost::filesystem;
 
@@ -24,33 +25,21 @@ const char CRLF[] = { '\r', '\n' };
 
 // -----------------------------------------------------------------------------
 
-bool Split2(const std::string& str, char token, std::string* part1,
-            std::string* part2) {
-  std::size_t pos = str.find(token);
-  if (pos == std::string::npos) {
+// Read entire file into string.
+static bool ReadFile(const Path& path, std::string* output) {
+  // Flag "ate": seek to the end of stream immediately after open.
+  bfs::ifstream stream{ path, std::ios::binary | std::ios::ate };
+  if (stream.fail()) {
     return false;
   }
 
-  *part1 = str.substr(0, pos);
-  *part2 = str.substr(pos + 1);
-
-  boost::trim(*part1);
-  boost::trim(*part2);
-
-  return true;
-}
-
-bool ReadFile(const Path& path, std::string* output) {
-  bfs::ifstream ifs{ path, std::ios::binary | std::ios::ate };
-  if (!ifs) {
+  auto size = stream.tellg();
+  output->resize(static_cast<std::size_t>(size), '\0');
+  stream.seekg(std::ios::beg);
+  stream.read(&(*output)[0], size);
+  if (stream.fail()) {
     return false;
   }
-
-  auto size = ifs.tellg();
-  output->resize(static_cast<std::size_t>(size), '\0');
-  ifs.seekg(0);
-  ifs.read(&(*output)[0], size);  // TODO: Error handling
-
   return true;
 }
 
diff --git a/webcc/common.h b/webcc/common.h
index 03140da..04979f1 100644
--- a/webcc/common.h
+++ b/webcc/common.h
@@ -21,15 +21,6 @@ using Payload = std::vector<boost::asio::const_buffer>;
 
 // -----------------------------------------------------------------------------
 
-// Split a string to two parts by the given token.
-bool Split2(const std::string& str, char token, std::string* part1,
-            std::string* part2);
-
-// Read entire file into string.
-bool ReadFile(const Path& path, std::string* output);
-
-// -----------------------------------------------------------------------------
-
 using Header = std::pair<std::string, std::string>;
 
 class Headers {
diff --git a/webcc/request.h b/webcc/request.h
index 5daeb83..543842c 100644
--- a/webcc/request.h
+++ b/webcc/request.h
@@ -68,7 +68,7 @@ public:
   }
 
   // Prepare payload.
-  void Prepare() final;
+  void Prepare() override;
 
 private:
   void CreateStartLine();
diff --git a/webcc/request_parser.cc b/webcc/request_parser.cc
index d872b7e..e050254 100644
--- a/webcc/request_parser.cc
+++ b/webcc/request_parser.cc
@@ -4,8 +4,9 @@
 
 #include "boost/algorithm/string.hpp"
 
-#include "webcc/request.h"
 #include "webcc/logger.h"
+#include "webcc/request.h"
+#include "webcc/utility.h"
 
 namespace webcc {
 
diff --git a/webcc/request_parser.h b/webcc/request_parser.h
index 93d1fc2..9c1e685 100644
--- a/webcc/request_parser.h
+++ b/webcc/request_parser.h
@@ -18,10 +18,10 @@ public:
   void Init(Request* request);
 
 private:
-  bool ParseStartLine(const std::string& line) final;
+  bool ParseStartLine(const std::string& line) override;
 
   // Override to handle multipart form data which is request only.
-  bool ParseContent(const char* data, std::size_t length) final;
+  bool ParseContent(const char* data, std::size_t length) override;
 
   // Multipart specific parsing helpers.
 
diff --git a/webcc/response.h b/webcc/response.h
index 9b4345e..861e97c 100644
--- a/webcc/response.h
+++ b/webcc/response.h
@@ -28,7 +28,7 @@ public:
   }
 
   // Set start line according to status code.
-  void Prepare() final;
+  void Prepare() override;
 
 private:
   int status_;
diff --git a/webcc/response_parser.cc b/webcc/response_parser.cc
index 31246a6..76e4e64 100644
--- a/webcc/response_parser.cc
+++ b/webcc/response_parser.cc
@@ -16,6 +16,7 @@ void ResponseParser::Init(Response* response) {
   response_ = response;
 }
 
+// TODO: Keep the original message.
 bool ResponseParser::ParseStartLine(const std::string& line) {
   std::vector<std::string> parts;
   boost::split(parts, line, boost::is_any_of(" "), boost::token_compress_on);
diff --git a/webcc/response_parser.h b/webcc/response_parser.h
index 83717f5..57f98bd 100644
--- a/webcc/response_parser.h
+++ b/webcc/response_parser.h
@@ -19,7 +19,7 @@ public:
 
 private:
   // Parse HTTP start line; E.g., "HTTP/1.1 200 OK".
-  bool ParseStartLine(const std::string& line) final;
+  bool ParseStartLine(const std::string& line) override;
 
   // The result response message.
   Response* response_;
diff --git a/webcc/rest_request_handler.h b/webcc/rest_request_handler.h
index 40b9993..5291c74 100644
--- a/webcc/rest_request_handler.h
+++ b/webcc/rest_request_handler.h
@@ -19,7 +19,7 @@ public:
   bool Bind(RestServicePtr service, const std::string& url, bool is_regex);
 
 private:
-  void HandleConnection(ConnectionPtr connection) final;
+  void HandleConnection(ConnectionPtr connection) override;
 
   void SetContent(RequestPtr request, ResponsePtr response,
                   std::string&& content);
diff --git a/webcc/rest_server.h b/webcc/rest_server.h
index 3111d85..91321a8 100644
--- a/webcc/rest_server.h
+++ b/webcc/rest_server.h
@@ -32,7 +32,7 @@ public:
   }
 
 private:
-  RequestHandler* GetRequestHandler() final {
+  RequestHandler* GetRequestHandler() override {
     return &request_handler_;
   }
 
diff --git a/webcc/socket.h b/webcc/socket.h
index da80cd7..2d6f3ec 100644
--- a/webcc/socket.h
+++ b/webcc/socket.h
@@ -47,14 +47,14 @@ public:
 
   void Connect(const std::string& host,
                const Endpoints& endpoints,
-               boost::system::error_code* ec) final;
+               boost::system::error_code* ec) override;
 
   void Write(const Request& request,
-             boost::system::error_code* ec) final;
+             boost::system::error_code* ec) override;
 
-  void AsyncReadSome(ReadHandler&& handler, std::vector<char>* buffer) final;
+  void AsyncReadSome(ReadHandler&& handler, std::vector<char>* buffer) override;
 
-  void Close(boost::system::error_code* ec) final;
+  void Close(boost::system::error_code* ec) override;
 
 private:
   boost::asio::ip::tcp::socket socket_;
@@ -71,14 +71,14 @@ public:
 
   void Connect(const std::string& host,
                const Endpoints& endpoints,
-               boost::system::error_code* ec) final;
+               boost::system::error_code* ec) override;
 
   void Write(const Request& request,
-             boost::system::error_code* ec) final;
+             boost::system::error_code* ec) override;
 
-  void AsyncReadSome(ReadHandler&& handler, std::vector<char>* buffer) final;
+  void AsyncReadSome(ReadHandler&& handler, std::vector<char>* buffer) override;
 
-  void Close(boost::system::error_code* ec) final;
+  void Close(boost::system::error_code* ec) override;
 
 private:
   void Handshake(const std::string& host, boost::system::error_code* ec);
diff --git a/webcc/utility.cc b/webcc/utility.cc
index 99580d6..a172a21 100644
--- a/webcc/utility.cc
+++ b/webcc/utility.cc
@@ -2,6 +2,7 @@
 
 #include <sstream>
 
+#include "boost/algorithm/string.hpp"
 #include "boost/uuid/random_generator.hpp"
 #include "boost/uuid/uuid_io.hpp"
 
@@ -14,4 +15,20 @@ std::string RandomUuid() {
   return ss.str();
 }
 
+bool Split2(const std::string& str, char token, std::string* part1,
+            std::string* part2) {
+  std::size_t pos = str.find(token);
+  if (pos == std::string::npos) {
+    return false;
+  }
+
+  *part1 = str.substr(0, pos);
+  *part2 = str.substr(pos + 1);
+
+  boost::trim(*part1);
+  boost::trim(*part2);
+
+  return true;
+}
+
 }  // namespace webcc
diff --git a/webcc/utility.h b/webcc/utility.h
index f4e6fcc..2b06d68 100644
--- a/webcc/utility.h
+++ b/webcc/utility.h
@@ -7,6 +7,10 @@ namespace webcc {
 
 std::string RandomUuid();
 
+// Split a string to two parts by the given token.
+bool Split2(const std::string& str, char token, std::string* part1,
+            std::string* part2);
+
 }  // namespace webcc
 
 #endif  // WEBCC_UTILITY_H_