diff --git a/README.md b/README.md
index a271cdd..344a804 100644
--- a/README.md
+++ b/README.md
@@ -32,14 +32,14 @@ func main() {
             "message_read",
         },
         Settings: ChannelSettings{
-            ReceiveMessageMode: "always",
+            ReceiveMessageMode: MsgModeAlways,
             SpamAllowed: false,
             Features: ChannelFeatures{
-            	StatusDelivered: "none",
-        	    MessageDeleting: "send",
-        	    MessageEditing: "both",
-        	    MessageQuoting: "both",
-        	    ImageMessage: "receive",
+            	StatusDelivered: ChannelFeatureNone,
+                MessageDeleting: ChannelFeatureSend,
+                MessageEditing:  ChannelFeatureBoth,
+                MessageQuoting:  ChannelFeatureBoth,
+                ImageMessage:    ChannelFeatureReceive,
             },
         },
     }
diff --git a/v1/client.go b/v1/client.go
index fa3108b..f64cef0 100644
--- a/v1/client.go
+++ b/v1/client.go
@@ -31,14 +31,14 @@ func New(url string, token string) *MgClient {
 // 			"message_read",
 // 		},
 //		Settings: ChannelSettings{
-// 			ReceiveMessageMode: "always",
+// 			ReceiveMessageMode: MsgModeAlways,
 //			SpamAllowed: false,
 //			Features: ChannelFeatures{
-//				StatusDelivered: "none",
-//				MessageDeleting: "send",
-//				MessageEditing: "both",
-//				MessageQuoting: "both",
-//				ImageMessage: "receive",
+//				StatusDelivered: ChannelFeatureNone,
+// 				MessageDeleting: ChannelFeatureSend,
+// 				MessageEditing:  ChannelFeatureBoth,
+// 				MessageQuoting:  ChannelFeatureBoth,
+// 				ImageMessage:    ChannelFeatureReceive,
 // 			},
 // 		},
 //	}
@@ -84,14 +84,14 @@ func (c *MgClient) ActivateTransportChannel(request Channel) (ActivateResponse,
 // 			"message_read",
 // 		},
 //		Settings: ChannelSettings{
-// 			ReceiveMessageMode: "always",
+// 			ReceiveMessageMode: MsgModeTimeLimited,
 //			SpamAllowed: false,
 //			Features: ChannelFeatures{
-//				StatusDelivered: "none",
-//				MessageDeleting: "send",
-//				MessageEditing: "both",
-//				MessageQuoting: "both",
-//				ImageMessage: "receive",
+//				StatusDelivered: ChannelFeatureNone,
+// 				MessageDeleting: ChannelFeatureSend,
+// 				MessageEditing:  ChannelFeatureBoth,
+// 				MessageQuoting:  ChannelFeatureBoth,
+// 				ImageMessage:    ChannelFeatureReceive,
 // 			},
 // 		},
 //	}
@@ -277,7 +277,7 @@ func (c *MgClient) DeleteMessage(request DeleteData) (MessagesResponse, int, err
 	outgoing, _ := json.Marshal(&request)
 
 	data, status, err := c.DeleteRequest(
-		"/messages/",
+		"/messages",
 		[]byte(outgoing),
 	)
 	if err != nil {
diff --git a/v1/client_test.go b/v1/client_test.go
index 332c392..b4248af 100644
--- a/v1/client_test.go
+++ b/v1/client_test.go
@@ -29,14 +29,14 @@ func TestMgClient_ActivateTransportChannel(t *testing.T) {
 			"message_read",
 		},
 		Settings: ChannelSettings{
-			ReceiveMessageMode: "always",
+			ReceiveMessageMode: MsgModeAlways,
 			SpamAllowed:        false,
 			Features: ChannelFeatures{
-				StatusDelivered: "none",
-				MessageDeleting: "send",
-				MessageEditing:  "both",
-				MessageQuoting:  "both",
-				ImageMessage:    "receive",
+				StatusDelivered: ChannelFeatureNone,
+				MessageDeleting: ChannelFeatureSend,
+				MessageEditing:  ChannelFeatureBoth,
+				MessageQuoting:  ChannelFeatureBoth,
+				ImageMessage:    ChannelFeatureReceive,
 			},
 		},
 	}
@@ -61,14 +61,14 @@ func TestMgClient_ActivateNewTransportChannel(t *testing.T) {
 			"message_read",
 		},
 		Settings: ChannelSettings{
-			ReceiveMessageMode: "always",
+			ReceiveMessageMode: MsgModeTimeLimited,
 			SpamAllowed:        false,
 			Features: ChannelFeatures{
-				StatusDelivered: "none",
-				MessageDeleting: "send",
-				MessageEditing:  "both",
-				MessageQuoting:  "both",
-				ImageMessage:    "receive",
+				StatusDelivered: ChannelFeatureNone,
+				MessageDeleting: ChannelFeatureSend,
+				MessageEditing:  ChannelFeatureBoth,
+				MessageQuoting:  ChannelFeatureBoth,
+				ImageMessage:    ChannelFeatureReceive,
 			},
 		},
 	}
@@ -108,11 +108,11 @@ func TestMgClient_UpdateTransportChannel(t *testing.T) {
 			ReceiveMessageMode: "always",
 			SpamAllowed:        false,
 			Features: ChannelFeatures{
-				StatusDelivered: "none",
-				MessageDeleting: "send",
-				MessageEditing:  "both",
-				MessageQuoting:  "both",
-				ImageMessage:    "receive",
+				StatusDelivered: ChannelFeatureNone,
+				MessageDeleting: ChannelFeatureSend,
+				MessageEditing:  ChannelFeatureBoth,
+				MessageQuoting:  ChannelFeatureBoth,
+				ImageMessage:    ChannelFeatureReceive,
 			},
 		},
 	}
diff --git a/v1/types.go b/v1/types.go
index efe8ee8..5a5982f 100644
--- a/v1/types.go
+++ b/v1/types.go
@@ -5,6 +5,17 @@ import (
 	"time"
 )
 
+const (
+	ChannelFeatureNone    string = "none"
+	ChannelFeatureReceive string = "receive"
+	ChannelFeatureSend    string = "send"
+	ChannelFeatureBoth    string = "both"
+
+	MsgModeNever       string = "never"
+	MsgModeTimeLimited string = "time-limited"
+	MsgModeAlways      string = "always"
+)
+
 // MgClient type
 type MgClient struct {
 	URL        string       `json:"url"`
@@ -59,22 +70,22 @@ type DeleteResponse struct {
 
 // User struct
 type User struct {
-	ExternalID string `json:"external_id" json:"external_id"`
-	Nickname   string `json:"nickname" json:"nickname"`
-	Firstname  string `json:"first_name,omitempty" json:"first_name"`
-	Lastname   string `json:"last_name,omitempty" json:"last_name"`
-	Avatar     string `json:"avatar,omitempty" json:"avatar"`
-	ProfileURL string `json:"profile_url,omitempty" json:"profile_url"`
-	Country    string `json:"country,omitempty" json:"country"`
-	Language   string `json:"language,omitempty" json:"language"`
-	Phone      string `json:"phone,omitempty" json:"phone"`
+	ExternalID string `json:"external_id"`
+	Nickname   string `json:"nickname"`
+	Firstname  string `json:"first_name,omitempty"`
+	Lastname   string `json:"last_name,omitempty"`
+	Avatar     string `json:"avatar,omitempty"`
+	ProfileURL string `json:"profile_url,omitempty"`
+	Country    string `json:"country,omitempty"`
+	Language   string `json:"language,omitempty"`
+	Phone      string `json:"phone,omitempty"`
 }
 
 // Message struct
 type Message struct {
-	ExternalID string `json:"external_id" json:"external_id"`
-	Type       string `json:"type,omitempty" json:"type"`
-	Text       string `json:"text,omitempty" json:"text"`
+	ExternalID string `json:"external_id"`
+	Type       string `json:"type,omitempty"`
+	Text       string `json:"text,omitempty"`
 }
 
 // SendMessage struct
@@ -91,11 +102,11 @@ type UpdateMessage struct {
 
 // SendData struct
 type SendData struct {
-	Message        SendMessage              `json:"message" json:"message"`
-	User           User                     `json:"user" json:"user"`
-	Channel        uint64                   `json:"channel" json:"channel"`
-	ExternalChatID string                   `json:"external_chat_id" json:"external_chat_id"`
-	Quote          *SendMessageRequestQuote `json:"quote,omitempty" json:"quote,omitempty"`
+	Message        SendMessage              `json:"message"`
+	User           User                     `json:"user"`
+	Channel        uint64                   `json:"channel"`
+	ExternalChatID string                   `json:"external_chat_id"`
+	Quote          *SendMessageRequestQuote `json:"quote,omitempty"`
 }
 
 type SendMessageRequestQuote struct {