diff --git a/libweave/examples/ubuntu/curl_http_client.cc b/libweave/examples/ubuntu/curl_http_client.cc
index 5cb4395..f8172bc 100644
--- a/libweave/examples/ubuntu/curl_http_client.cc
+++ b/libweave/examples/ubuntu/curl_http_client.cc
@@ -7,6 +7,7 @@
 #include <base/bind.h>
 #include <curl/curl.h>
 #include <weave/provider/task_runner.h>
+#include <weave/enum_to_string.h>
 
 namespace weave {
 namespace examples {
@@ -40,7 +41,7 @@
       FROM_HERE, base::Bind(error_callback, base::Owned(error.release())), {});
 }
 
-void CurlHttpClient::SendRequest(const std::string& method,
+void CurlHttpClient::SendRequest(Method method,
                                  const std::string& url,
                                  const Headers& headers,
                                  const std::string& data,
@@ -50,13 +51,18 @@
                                                            &curl_easy_cleanup};
   CHECK(curl);
 
-  if (method == "GET") {
+  switch (method) {
+    case Method::kGet:
     CHECK_EQ(CURLE_OK, curl_easy_setopt(curl.get(), CURLOPT_HTTPGET, 1L));
-  } else if (method == "POST") {
+    break;
+    case Method::kPost:
     CHECK_EQ(CURLE_OK, curl_easy_setopt(curl.get(), CURLOPT_HTTPPOST, 1L));
-  } else {
-    CHECK_EQ(CURLE_OK, curl_easy_setopt(curl.get(), CURLOPT_CUSTOMREQUEST,
-                                        method.c_str()));
+    break;
+    case Method::kPatch:
+    case Method::kPut:
+      CHECK_EQ(CURLE_OK, curl_easy_setopt(curl.get(), CURLOPT_CUSTOMREQUEST,
+                                          weave::EnumToString(method).c_str()));
+      break;
   }
 
   CHECK_EQ(CURLE_OK, curl_easy_setopt(curl.get(), CURLOPT_URL, url.c_str()));
@@ -67,7 +73,7 @@
 
   CHECK_EQ(CURLE_OK, curl_easy_setopt(curl.get(), CURLOPT_HTTPHEADER, chunk));
 
-  if (!data.empty() || method == "POST") {
+  if (!data.empty() || method == Method::kPost) {
     CHECK_EQ(CURLE_OK,
              curl_easy_setopt(curl.get(), CURLOPT_POSTFIELDS, data.c_str()));
   }
diff --git a/libweave/examples/ubuntu/curl_http_client.h b/libweave/examples/ubuntu/curl_http_client.h
index 033102d..a5090ff 100644
--- a/libweave/examples/ubuntu/curl_http_client.h
+++ b/libweave/examples/ubuntu/curl_http_client.h
@@ -24,7 +24,7 @@
  public:
   explicit CurlHttpClient(provider::TaskRunner* task_runner);
 
-  void SendRequest(const std::string& method,
+  void SendRequest(Method method,
                    const std::string& url,
                    const Headers& headers,
                    const std::string& data,
diff --git a/libweave/examples/ubuntu/event_http_client.cc b/libweave/examples/ubuntu/event_http_client.cc
index 742eef8..b24c075 100644
--- a/libweave/examples/ubuntu/event_http_client.cc
+++ b/libweave/examples/ubuntu/event_http_client.cc
@@ -93,14 +93,14 @@
 EventHttpClient::EventHttpClient(EventTaskRunner* task_runner)
     : task_runner_{task_runner} {}
 
-void EventHttpClient::SendRequest(const std::string& method,
+void EventHttpClient::SendRequest(Method method,
                                   const std::string& url,
                                   const Headers& headers,
                                   const std::string& data,
                                   const SuccessCallback& success_callback,
                                   const ErrorCallback& error_callback) {
   evhttp_cmd_type method_id;
-  CHECK(weave::StringToEnum(method, &method_id));
+  CHECK(weave::StringToEnum(weave::EnumToString(method), &method_id));
   std::unique_ptr<evhttp_uri, EventDeleter> http_uri{
       evhttp_uri_parse(url.c_str())};
   CHECK(http_uri);
@@ -146,7 +146,8 @@
     return;
   ErrorPtr error;
   Error::AddToPrintf(&error, FROM_HERE, "http_client", "request_failed",
-                     "request failed: %s %s", method.c_str(), url.c_str());
+                     "request failed: %s %s", EnumToString(method).c_str(),
+                     url.c_str());
   task_runner_->PostDelayedTask(FROM_HERE,
                                 base::Bind(error_callback, error.get()), {});
 }
diff --git a/libweave/examples/ubuntu/event_http_client.h b/libweave/examples/ubuntu/event_http_client.h
index 53a01ab..457e550 100644
--- a/libweave/examples/ubuntu/event_http_client.h
+++ b/libweave/examples/ubuntu/event_http_client.h
@@ -20,7 +20,7 @@
  public:
   explicit EventHttpClient(EventTaskRunner* task_runner);
 
-  void SendRequest(const std::string& method,
+  void SendRequest(Method method,
                    const std::string& url,
                    const Headers& headers,
                    const std::string& data,
diff --git a/libweave/include/weave/enum_to_string.h b/libweave/include/weave/enum_to_string.h
index d6c2b79..503b753 100644
--- a/libweave/include/weave/enum_to_string.h
+++ b/libweave/include/weave/enum_to_string.h
@@ -52,7 +52,7 @@
       return m.name;
     }
   }
-  NOTREACHED();
+  NOTREACHED() << static_cast<int>(id);
   return std::string();
 }
 
diff --git a/libweave/include/weave/provider/http_client.h b/libweave/include/weave/provider/http_client.h
index 995e7d6..24b4588 100644
--- a/libweave/include/weave/provider/http_client.h
+++ b/libweave/include/weave/provider/http_client.h
@@ -17,6 +17,13 @@
 
 class HttpClient {
  public:
+  enum class Method {
+    kGet,
+    kPatch,
+    kPost,
+    kPut,
+  };
+
   class Response {
    public:
     virtual int GetStatusCode() const = 0;
@@ -29,7 +36,7 @@
   using Headers = std::vector<std::pair<std::string, std::string>>;
   using SuccessCallback = base::Callback<void(const Response&)>;
 
-  virtual void SendRequest(const std::string& method,
+  virtual void SendRequest(Method method,
                            const std::string& url,
                            const Headers& headers,
                            const std::string& data,
diff --git a/libweave/include/weave/provider/test/mock_http_client.h b/libweave/include/weave/provider/test/mock_http_client.h
index 8a9f955..72cb9b8 100644
--- a/libweave/include/weave/provider/test/mock_http_client.h
+++ b/libweave/include/weave/provider/test/mock_http_client.h
@@ -28,7 +28,7 @@
   ~MockHttpClient() override = default;
 
   MOCK_METHOD6(SendRequest,
-               void(const std::string&,
+               void(Method,
                     const std::string&,
                     const Headers&,
                     const std::string&,
diff --git a/libweave/src/device_registration_info.cc b/libweave/src/device_registration_info.cc
index 7960b77..5a5fb0d 100644
--- a/libweave/src/device_registration_info.cc
+++ b/libweave/src/device_registration_info.cc
@@ -113,7 +113,7 @@
 
 class RequestSender final {
  public:
-  RequestSender(const std::string& method,
+  RequestSender(HttpClient::Method method,
                 const std::string& url,
                 HttpClient* transport)
       : method_{method}, url_{url}, transport_{transport} {}
@@ -122,8 +122,8 @@
             const ErrorCallback& error_callback) {
     static int debug_id = 0;
     ++debug_id;
-    VLOG(1) << "Sending request. id:" << debug_id << " method:" << method_
-            << " url:" << url_;
+    VLOG(1) << "Sending request. id:" << debug_id
+            << " method:" << EnumToString(method_) << " url:" << url_;
     VLOG(2) << "Request data: " << data_;
     auto on_success = [](int debug_id,
                          const HttpClient::SuccessCallback& success_callback,
@@ -175,7 +175,7 @@
     return headers;
   }
 
-  std::string method_;
+  HttpClient::Method method_;
   std::string url_;
   std::string data_;
   std::string mime_type_;
@@ -380,7 +380,8 @@
       std::make_shared<base::Closure>(success_callback);
   auto shared_error_callback = std::make_shared<ErrorCallback>(error_callback);
 
-  RequestSender sender{http::kPost, GetOAuthURL("token"), http_client_};
+  RequestSender sender{HttpClient::Method::kPost, GetOAuthURL("token"),
+                       http_client_};
   sender.SetFormData({
       {"refresh_token", GetSettings().refresh_token},
       {"client_id", GetSettings().client_id},
@@ -532,8 +533,8 @@
       error_callback.Run(error.get());
     return;
   }
-  DoCloudRequest(http::kGet, GetDeviceURL(), nullptr, success_callback,
-                 error_callback);
+  DoCloudRequest(HttpClient::Method::kGet, GetDeviceURL(), nullptr,
+                 success_callback, error_callback);
 }
 
 struct DeviceRegistrationInfo::RegisterCallbacks {
@@ -574,7 +575,7 @@
   auto url = GetServiceURL("registrationTickets/" + ticket_id,
                            {{"key", GetSettings().api_key}});
 
-  RequestSender sender{http::kPatch, url, http_client_};
+  RequestSender sender{HttpClient::Method::kPatch, url, http_client_};
   sender.SetJsonData(req_json);
   sender.Send(base::Bind(&DeviceRegistrationInfo::RegisterDeviceOnTicketSent,
                          weak_factory_.GetWeakPtr(), ticket_id, callbacks),
@@ -599,7 +600,7 @@
   std::string url =
       GetServiceURL("registrationTickets/" + ticket_id + "/finalize",
                     {{"key", GetSettings().api_key}});
-  RequestSender{http::kPost, url, http_client_}.Send(
+  RequestSender{HttpClient::Method::kPost, url, http_client_}.Send(
       base::Bind(&DeviceRegistrationInfo::RegisterDeviceOnTicketFinalized,
                  weak_factory_.GetWeakPtr(), callbacks),
       base::Bind(&DeviceRegistrationInfo::RegisterDeviceError,
@@ -634,7 +635,8 @@
   UpdateDeviceInfoTimestamp(*device_draft_response);
 
   // Now get access_token and refresh_token
-  RequestSender sender2{http::kPost, GetOAuthURL("token"), http_client_};
+  RequestSender sender2{HttpClient::Method::kPost, GetOAuthURL("token"),
+                        http_client_};
   sender2.SetFormData(
       {{"code", auth_code},
        {"client_id", GetSettings().client_id},
@@ -686,7 +688,7 @@
 }
 
 void DeviceRegistrationInfo::DoCloudRequest(
-    const std::string& method,
+    HttpClient::Method method,
     const std::string& url,
     const base::DictionaryValue* body,
     const CloudRequestCallback& success_callback,
@@ -901,8 +903,8 @@
     const base::DictionaryValue& command_patch,
     const base::Closure& on_success,
     const base::Closure& on_error) {
-  DoCloudRequest(http::kPatch, GetServiceURL("commands/" + command_id),
-                 &command_patch,
+  DoCloudRequest(HttpClient::Method::kPatch,
+                 GetServiceURL("commands/" + command_id), &command_patch,
                  base::Bind(&IgnoreCloudResultWithCallback, on_success),
                  base::Bind(&IgnoreCloudErrorWithCallback, on_error));
 }
@@ -969,7 +971,7 @@
       {}, {{"lastUpdateTimeMs", last_device_resource_updated_timestamp_}});
 
   DoCloudRequest(
-      http::kPut, url, device_resource.get(),
+      HttpClient::Method::kPut, url, device_resource.get(),
       base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceSuccess,
                  AsWeakPtr()),
       base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceError,
@@ -1061,7 +1063,7 @@
   fetch_commands_request_sent_ = true;
   fetch_commands_request_queued_ = false;
   DoCloudRequest(
-      http::kGet,
+      HttpClient::Method::kGet,
       GetServiceURL("commands/queue", {{"deviceId", GetSettings().cloud_id}}),
       nullptr, base::Bind(&DeviceRegistrationInfo::OnFetchCommandsSuccess,
                           AsWeakPtr(), on_success),
@@ -1105,8 +1107,9 @@
       std::unique_ptr<base::DictionaryValue> cmd_copy{command_dict->DeepCopy()};
       cmd_copy->SetString("state", "aborted");
       // TODO(wiley) We could consider handling this error case more gracefully.
-      DoCloudRequest(http::kPut, GetServiceURL("commands/" + command_id),
-                     cmd_copy.get(), base::Bind(&IgnoreCloudResult),
+      DoCloudRequest(HttpClient::Method::kPut,
+                     GetServiceURL("commands/" + command_id), cmd_copy.get(),
+                     base::Bind(&IgnoreCloudResult),
                      base::Bind(&IgnoreCloudError));
     } else {
       // Normal command, publish it to local clients.
@@ -1197,7 +1200,7 @@
 
   device_state_update_pending_ = true;
   DoCloudRequest(
-      http::kPost, GetDeviceURL("patchState"), &body,
+      HttpClient::Method::kPost, GetDeviceURL("patchState"), &body,
       base::Bind(&DeviceRegistrationInfo::OnPublishStateSuccess, AsWeakPtr(),
                  update_id),
       base::Bind(&DeviceRegistrationInfo::OnPublishStateError, AsWeakPtr()));
diff --git a/libweave/src/device_registration_info.h b/libweave/src/device_registration_info.h
index 8d230a9..1577cd4 100644
--- a/libweave/src/device_registration_info.h
+++ b/libweave/src/device_registration_info.h
@@ -176,7 +176,7 @@
   // and device removal.  It is a recommended way to do cloud API
   // requests.
   // TODO(antonm): Consider moving into some other class.
-  void DoCloudRequest(const std::string& method,
+  void DoCloudRequest(provider::HttpClient::Method method,
                       const std::string& url,
                       const base::DictionaryValue* body,
                       const CloudRequestCallback& success_callback,
@@ -184,7 +184,7 @@
 
   // Helper for DoCloudRequest().
   struct CloudRequestData {
-    std::string method;
+    provider::HttpClient::Method method;
     std::string url;
     std::string body;
     CloudRequestCallback success_callback;
diff --git a/libweave/src/device_registration_info_unittest.cc b/libweave/src/device_registration_info_unittest.cc
index 41b6d78..49c4ccb 100644
--- a/libweave/src/device_registration_info_unittest.cc
+++ b/libweave/src/device_registration_info_unittest.cc
@@ -233,9 +233,10 @@
   EXPECT_FALSE(dev_reg_->HaveRegistrationCredentials());
   ReloadSettings();
 
-  EXPECT_CALL(http_client_,
-              SendRequest(http::kPost, dev_reg_->GetOAuthURL("token"),
-                          HttpClient::Headers{GetFormHeader()}, _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
+                  HttpClient::Headers{GetFormHeader()}, _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
           const HttpClient::SuccessCallback& callback) {
@@ -261,9 +262,10 @@
   ReloadSettings();
   EXPECT_EQ(GcdState::kConnecting, GetGcdState());
 
-  EXPECT_CALL(http_client_,
-              SendRequest(http::kPost, dev_reg_->GetOAuthURL("token"),
-                          HttpClient::Headers{GetFormHeader()}, _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
+                  HttpClient::Headers{GetFormHeader()}, _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
           const HttpClient::SuccessCallback& callback) {
@@ -289,9 +291,10 @@
   ReloadSettings();
   EXPECT_EQ(GcdState::kConnecting, GetGcdState());
 
-  EXPECT_CALL(http_client_,
-              SendRequest(http::kPost, dev_reg_->GetOAuthURL("token"),
-                          HttpClient::Headers{GetFormHeader()}, _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
+                  HttpClient::Headers{GetFormHeader()}, _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
           const HttpClient::SuccessCallback& callback) {
@@ -318,7 +321,7 @@
   SetAccessToken();
 
   EXPECT_CALL(http_client_,
-              SendRequest(http::kGet, dev_reg_->GetDeviceURL(),
+              SendRequest(HttpClient::Method::kGet, dev_reg_->GetDeviceURL(),
                           HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
                           _, _, _))
       .WillOnce(WithArgs<3, 4>(
@@ -382,10 +385,10 @@
 
   std::string ticket_url = dev_reg_->GetServiceURL("registrationTickets/") +
                            test_data::kClaimTicketId;
-  EXPECT_CALL(
-      http_client_,
-      SendRequest(http::kPatch, ticket_url + "?key=" + test_data::kApiKey,
-                  HttpClient::Headers{GetJsonHeader()}, _, _, _))
+  EXPECT_CALL(http_client_,
+              SendRequest(HttpClient::Method::kPatch,
+                          ticket_url + "?key=" + test_data::kApiKey,
+                          HttpClient::Headers{GetJsonHeader()}, _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
           const HttpClient::SuccessCallback& callback) {
@@ -452,7 +455,7 @@
       })));
 
   EXPECT_CALL(http_client_,
-              SendRequest(http::kPost,
+              SendRequest(HttpClient::Method::kPost,
                           ticket_url + "/finalize?key=" + test_data::kApiKey,
                           HttpClient::Headers{}, _, _, _))
       .WillOnce(
@@ -471,9 +474,10 @@
             callback.Run(*ReplyWithJson(200, json));
           })));
 
-  EXPECT_CALL(http_client_,
-              SendRequest(http::kPost, dev_reg_->GetOAuthURL("token"),
-                          HttpClient::Headers{GetFormHeader()}, _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
+                  HttpClient::Headers{GetFormHeader()}, _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
           const HttpClient::SuccessCallback& callback) {
@@ -572,7 +576,7 @@
 
 TEST_F(DeviceRegistrationInfoUpdateCommandTest, SetProgress) {
   EXPECT_CALL(http_client_,
-              SendRequest(http::kPatch, command_url_,
+              SendRequest(HttpClient::Method::kPatch, command_url_,
                           HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
                           _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
@@ -589,7 +593,7 @@
 
 TEST_F(DeviceRegistrationInfoUpdateCommandTest, Complete) {
   EXPECT_CALL(http_client_,
-              SendRequest(http::kPatch, command_url_,
+              SendRequest(HttpClient::Method::kPatch, command_url_,
                           HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
                           _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
@@ -606,7 +610,7 @@
 
 TEST_F(DeviceRegistrationInfoUpdateCommandTest, Cancel) {
   EXPECT_CALL(http_client_,
-              SendRequest(http::kPatch, command_url_,
+              SendRequest(HttpClient::Method::kPatch, command_url_,
                           HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
                           _, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
diff --git a/libweave/src/http_constants.cc b/libweave/src/http_constants.cc
index e80aae4..445ff75 100644
--- a/libweave/src/http_constants.cc
+++ b/libweave/src/http_constants.cc
@@ -4,14 +4,12 @@
 
 #include "src/http_constants.h"
 
+#include <weave/provider/http_client.h>
+#include <weave/enum_to_string.h>
+
 namespace weave {
 namespace http {
 
-const char kGet[] = "GET";
-const char kPatch[] = "PATCH";
-const char kPost[] = "POST";
-const char kPut[] = "PUT";
-
 const char kAuthorization[] = "Authorization";
 const char kContentType[] = "Content-Type";
 
@@ -21,4 +19,21 @@
 const char kWwwFormUrlEncoded[] = "application/x-www-form-urlencoded";
 
 }  // namespace http
+
+using provider::HttpClient;
+
+namespace {
+
+const weave::EnumToStringMap<HttpClient::Method>::Map kMapMethod[] = {
+    {HttpClient::Method::kGet, "GET"},
+    {HttpClient::Method::kPost, "POST"},
+    {HttpClient::Method::kPut, "PUT"},
+    {HttpClient::Method::kPatch, "PATCH"}};
+
+}  // namespace
+
+template <>
+LIBWEAVE_EXPORT EnumToStringMap<HttpClient::Method>::EnumToStringMap()
+    : EnumToStringMap(kMapMethod) {}
+
 }  // namespace weave
diff --git a/libweave/src/http_constants.h b/libweave/src/http_constants.h
index f219a3c..973190e 100644
--- a/libweave/src/http_constants.h
+++ b/libweave/src/http_constants.h
@@ -18,11 +18,6 @@
 const int kServiceUnavailable = 503;
 const int kNotSupported = 501;
 
-extern const char kGet[];
-extern const char kPatch[];
-extern const char kPost[];
-extern const char kPut[];
-
 extern const char kAuthorization[];
 extern const char kContentType[];
 
diff --git a/libweave/src/weave_unittest.cc b/libweave/src/weave_unittest.cc
index 8eb6a54..5e15212 100644
--- a/libweave/src/weave_unittest.cc
+++ b/libweave/src/weave_unittest.cc
@@ -36,10 +36,11 @@
 
 namespace weave {
 
+using provider::HttpClient;
+using provider::Network;
+using provider::test::MockHttpClientResponse;
 using test::CreateDictionaryValue;
 using test::ValueToString;
-using provider::test::MockHttpClientResponse;
-using provider::Network;
 
 const char kCommandDefs[] = R"({
   "base": {
@@ -136,12 +137,12 @@
  protected:
   void SetUp() override {}
 
-  void ExpectRequest(const std::string& method,
+  void ExpectRequest(HttpClient::Method method,
                      const std::string& url,
                      const std::string& json_response) {
     EXPECT_CALL(http_client_, SendRequest(method, url, _, _, _, _))
         .WillOnce(WithArgs<4>(Invoke([json_response](
-            const provider::HttpClient::SuccessCallback& callback) {
+            const HttpClient::SuccessCallback& callback) {
           std::unique_ptr<provider::test::MockHttpClientResponse> response{
               new StrictMock<provider::test::MockHttpClientResponse>};
           EXPECT_CALL(*response, GetStatusCode())
@@ -312,7 +313,7 @@
   auto response = CreateDictionaryValue(kRegistrationResponse);
   response->Set("deviceDraft", draft->DeepCopy());
   ExpectRequest(
-      "PATCH",
+      HttpClient::Method::kPatch,
       "https://www.googleapis.com/clouddevices/v1/registrationTickets/"
       "TICKET_ID?key=TEST_API_KEY",
       ValueToString(*response));
@@ -320,12 +321,13 @@
   response = CreateDictionaryValue(kRegistrationFinalResponse);
   response->Set("deviceDraft", draft->DeepCopy());
   ExpectRequest(
-      "POST",
+      HttpClient::Method::kPost,
       "https://www.googleapis.com/clouddevices/v1/registrationTickets/"
       "TICKET_ID/finalize?key=TEST_API_KEY",
       ValueToString(*response));
 
-  ExpectRequest("POST", "https://accounts.google.com/o/oauth2/token",
+  ExpectRequest(HttpClient::Method::kPost,
+                "https://accounts.google.com/o/oauth2/token",
                 kAuthTokenResponse);
 
   InitDnsSdPublishing(true, "DB");