diff --git a/database/contacts.go b/database/contacts.go
index 893112d..682b5f3 100644
--- a/database/contacts.go
+++ b/database/contacts.go
@@ -5,13 +5,11 @@ import (
 	"errors"
 	"fmt"
 	"github.com/google/uuid"
-	"log"
 	"relay-server/helpers"
 	"relay-server/model"
 )
 
-func DeleteContact(db *sql.DB, userID uuid.UUID, conversationID uuid.UUID) (string, error) {
-	// Check conversation type
+func DeleteContact(db *sql.DB, userID uuid.UUID, conversationID uuid.UUID) error {
 	var conversationType string
 	err := db.QueryRow(
 		"SELECT conversation_type FROM Conversations WHERE conversation_id = $1",
@@ -19,185 +17,151 @@ func DeleteContact(db *sql.DB, userID uuid.UUID, conversationID uuid.UUID) (stri
 	).Scan(&conversationType)
 	if err != nil {
 		if errors.Is(err, sql.ErrNoRows) {
-			return "no conversation found for this id", nil
+			return helpers.NewError(helpers.ErrNotFound, "no contacts found for this id", fmt.Errorf("no conversation found with id: %s", conversationID))
 		}
-		return "", fmt.Errorf("error checking conversation type: %w", err)
+		return helpers.NewError(helpers.ErrInternal, "Failed to check conversation", err)
 	}
 
 	if conversationType == "group" {
 		// Delete from Contacts
 		res, err := db.Exec(
 			"DELETE FROM Contacts WHERE conversation_id = $1 AND user_id = $2",
-			conversationID,
-			userID,
+			conversationID, userID,
 		)
 		if err != nil {
-			return "", fmt.Errorf("error deleting contact: %w", err)
+			return helpers.NewError(helpers.ErrInternal, "Failed to delete contact", err)
 		}
 
 		rowsAffected, err := res.RowsAffected()
 		if err != nil {
-			return "", fmt.Errorf("error checking contact deletion: %w", err)
+			return helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to verify contact deletion: %w", err))
 		}
 		if rowsAffected == 0 {
-			return fmt.Sprintf("no matching contact found with conversation id: %s, user id: %s", conversationID, userID), nil
+			return helpers.NewError(helpers.ErrNotFound, fmt.Sprintf("no matching contact found with conversation id: %s, user id: %s", conversationID, userID), nil)
 		}
 
 		// Delete from Memberships
 		res, err = db.Exec(
 			"DELETE FROM Memberships WHERE conversation_id = $1 AND user_id = $2",
-			conversationID,
-			userID,
+			conversationID, userID,
 		)
 		if err != nil {
-			return "", fmt.Errorf("error deleting membership: %w", err)
+			return helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to delete membership: %w", err))
 		}
 
 		rowsAffected, err = res.RowsAffected()
 		if err != nil {
-			return "", fmt.Errorf("error checking membership deletion: %w", err)
+			return helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to verify membership deletion: %w", err))
 		}
 		if rowsAffected == 0 {
-			return "", fmt.Errorf("no matching membership found with conversation id: %s, user id: %s", conversationID, userID)
+			return helpers.NewError(helpers.ErrNotFound, "No membership found", err)
 		}
 	} else {
-		// Handle direct conversation
 		res, err := db.Exec(
 			"DELETE FROM Contacts WHERE user_id = $1 AND conversation_id = $2",
-			userID,
-			conversationID,
+			userID, conversationID,
 		)
 		if err != nil {
-			return "", fmt.Errorf("error deleting contact: %w", err)
+			return helpers.NewError(helpers.ErrInternal, "Failed to delete contact", err)
 		}
 
 		rowsAffected, err := res.RowsAffected()
 		if err != nil {
-			return "", fmt.Errorf("error checking contact deletion: %w", err)
+			return helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to verify contact deletion: %w", err))
 		}
 		if rowsAffected == 0 {
-			return fmt.Sprintf("no matching contact found with user id: %s, conversation id: %s", userID, conversationID), nil
+			return helpers.NewError(helpers.ErrNotFound, fmt.Sprintf("no matching contact found with user id: %s, conversation id: %s", userID, conversationID), nil)
 		}
-
-		fmt.Printf("Successfully deleted contact for user %s in conversation %s", userID, conversationID)
 	}
 
-	return "", nil
+	return nil
 }
 
 func InsertContact(db *sql.DB, userID uuid.UUID, contactID uuid.UUID, contactUsername string) (*model.Contact, error) {
 	isSelfContact := userID == contactID
-	var contact model.Contact
 	var conversationID uuid.UUID
 
 	if isSelfContact {
-		findSelfConversationQuery := `
-        SELECT c.conversation_id
-        FROM Conversations c
-        JOIN Memberships m ON c.conversation_id = m.conversation_id
-        WHERE c.conversation_type = 'direct'
-        AND m.user_id = $1
-        AND (
-          SELECT COUNT(*)
-          FROM Memberships
-          WHERE conversation_id = c.conversation_id
-        ) = 1
-        LIMIT 1;
-      `
+		err := db.QueryRow(`
+            SELECT c.conversation_id
+            FROM Conversations c
+            JOIN Memberships m ON c.conversation_id = m.conversation_id
+            WHERE c.conversation_type = 'direct'
+            AND m.user_id = $1
+            AND (SELECT COUNT(*) FROM Memberships WHERE conversation_id = c.conversation_id) = 1
+            LIMIT 1;
+        `, userID).Scan(&conversationID)
 
-		err := db.QueryRow(findSelfConversationQuery, userID).Scan(&conversationID)
-		if err != nil {
-			if errors.Is(err, sql.ErrNoRows) {
-				conversationID = uuid.Nil
-			}
-			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error finding existing conversation: %w", err))
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to check existing conversation: %w", err))
 		}
 
-		// if conversation for themselves don't exist
 		if conversationID == uuid.Nil {
-			createConversationQuery := `
-          INSERT INTO Conversations (conversation_type)
-          VALUES ('direct')
-          RETURNING conversation_id;
-        `
-			err := db.QueryRow(createConversationQuery).Scan(&conversationID)
+			err := db.QueryRow(`
+                INSERT INTO Conversations (conversation_type)
+                VALUES ('direct')
+                RETURNING conversation_id;
+            `).Scan(&conversationID)
 			if err != nil {
-				return nil, helpers.NewError(helpers.ErrInternal, "Internal server error", fmt.Errorf("error creating conversation for self-contact: %w", err))
+				return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to create conversation: %w", err))
 			}
 
-			createMembershipQuery := `
-          INSERT INTO Memberships (conversation_id, user_id)
-          VALUES ($1, $2)
-          ON CONFLICT (conversation_id, user_id) DO NOTHING;
-        `
-			_, err = db.Exec(createMembershipQuery, conversationID, userID)
-
-		} else {
-			// For regular contacts, check if a conversation already exists between the two users
-			findConversationQuery := `
-     		  SELECT c.conversation_id
-     		  FROM Conversations c
-     		  JOIN Memberships m1 ON c.conversation_id = m1.conversation_id
-     		  JOIN Memberships m2 ON c.conversation_id = m2.conversation_id
-     		  WHERE c.conversation_type = 'direct'
-     		  AND (
-     		    (m1.user_id = $1 AND m2.user_id = $2)
-     		    OR 
-     		    (m1.user_id = $2 AND m2.user_id = $1)
-     		  )
-     		  LIMIT 1;
-     		`
-			err := db.QueryRow(findConversationQuery, userID, contactID).Scan(&conversationID)
+			_, err = db.Exec(`
+                INSERT INTO Memberships (conversation_id, user_id)
+                VALUES ($1, $2)
+                ON CONFLICT (conversation_id, user_id) DO NOTHING;
+            `, conversationID, userID)
 			if err != nil {
-				if errors.Is(err, sql.ErrNoRows) {
-					conversationID = uuid.Nil
-				}
-				return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error finding existing conversation: %w", err))
-			}
-			if conversationID != uuid.Nil {
-				// Create a new conversation between user and contact
-				createConversationQuery := `
-        		  INSERT INTO Conversations (conversation_type)
-        		  VALUES ('direct')
-        		  RETURNING conversation_id;
-        		`
-				err := db.QueryRow(createConversationQuery).Scan(&conversationID)
-				if err != nil {
-					return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error creating conversation: %w", err))
-				}
-
-				createMembershipQuery := `
-        		  INSERT INTO Memberships (conversation_id, user_id)
-        		  VALUES ($1, $2), ($1, $3)
-        		  ON CONFLICT (conversation_id, user_id) DO NOTHING;
-        		`
-
-				res, err := db.Exec(createMembershipQuery, conversationID, userID, contactID)
-				if err != nil {
-					return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error creating membership: %w", err))
-				}
-				rowsAffected, err := res.RowsAffected()
-				if err != nil {
-					return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error checking membership creation: %w", err))
-				}
-				if rowsAffected == 0 {
-					return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error creating membership %w", err))
-				}
+				return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to create membership: %w", err))
 			}
 		}
+	} else {
+		err := db.QueryRow(`
+            SELECT c.conversation_id
+            FROM Conversations c
+            JOIN Memberships m1 ON c.conversation_id = m1.conversation_id
+            JOIN Memberships m2 ON c.conversation_id = m2.conversation_id
+            WHERE c.conversation_type = 'direct'
+            AND ((m1.user_id = $1 AND m2.user_id = $2) OR (m1.user_id = $2 AND m2.user_id = $1))
+            LIMIT 1;
+        `, userID, contactID).Scan(&conversationID)
 
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to check existing conversation %w", err))
+		}
+
+		if conversationID == uuid.Nil {
+			err := db.QueryRow(`
+                INSERT INTO Conversations (conversation_type)
+                VALUES ('direct')
+                RETURNING conversation_id;
+            `).Scan(&conversationID)
+			if err != nil {
+				return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to create conversation: %w", err))
+			}
+
+			_, err = db.Exec(`
+                INSERT INTO Memberships (conversation_id, user_id)
+                VALUES ($1, $2), ($1, $3)
+                ON CONFLICT (conversation_id, user_id) DO NOTHING;
+            `, conversationID, userID, contactID)
+			if err != nil {
+				return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to create memberships: %w", err))
+			}
+		}
 	}
+
 	insertedContact, err := InsertContactByID(db, contactID, conversationID)
-	if err != nil || insertedContact.UserID == uuid.Nil {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", err)
+	if err != nil {
+		return nil, err
 	}
 
 	latestMessage, err := GetLatestMessage(db, conversationID)
 	if err != nil {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", err)
+		return nil, err
 	}
 
-	contact = model.Contact{
+	contact := model.Contact{
 		ID:                insertedContact.ID,
 		ConversationID:    insertedContact.ConversationID,
 		UserID:            insertedContact.UserID,
@@ -213,30 +177,29 @@ func InsertContact(db *sql.DB, userID uuid.UUID, contactID uuid.UUID, contactUse
 
 func InsertContactByID(db *sql.DB, userID uuid.UUID, conversationID uuid.UUID) (*model.Contact, error) {
 	// First check if contact already exists
-	checkQuery := `
-  	  SELECT contact_id, conversation_id, user_id
-  	  FROM Contacts 
-  	  WHERE user_id = $1 AND conversation_id = $2
-  	`
 	var contact model.Contact
-	err := db.QueryRow(checkQuery, userID, conversationID).Scan(&contact.ID, &contact.ConversationID, &contact.UserID)
+	err := db.QueryRow(`
+        SELECT contact_id, conversation_id, user_id
+        FROM Contacts 
+        WHERE user_id = $1 AND conversation_id = $2
+    `, userID, conversationID).Scan(&contact.ID, &contact.ConversationID, &contact.UserID)
+
 	if err == nil {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("contact already exists"))
+		return nil, helpers.NewError(helpers.ErrInvalidInput, "Contact already exists", nil)
 	} else if !errors.Is(err, sql.ErrNoRows) {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error checking contact existence: %w", err))
+		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to check contact existence: %w", err))
 	}
 
-	insertQuery := `
-    	  INSERT INTO Contacts (user_id, conversation_id)
-    	  VALUES($1, $2)
-    	  RETURNING contact_id, conversation_id, user_id
-    	`
+	// Insert new contact
+	err = db.QueryRow(`
+        INSERT INTO Contacts (user_id, conversation_id)
+        VALUES($1, $2)
+        RETURNING contact_id, conversation_id, user_id
+    `, userID, conversationID).Scan(&contact.ID, &contact.ConversationID, &contact.UserID)
 
-	err = db.QueryRow(insertQuery, userID, conversationID).Scan(&contact.ID, &contact.ConversationID, &contact.UserID)
 	if err != nil {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error inserting contact: %w", err))
+		return nil, helpers.NewError(helpers.ErrInternal, "Failed to create contact", err)
 	}
-	fmt.Printf("Successfully inserted contact by id: %v", conversationID)
 
 	return &contact, nil
 }
@@ -244,23 +207,31 @@ func InsertContactByID(db *sql.DB, userID uuid.UUID, conversationID uuid.UUID) (
 func GetLatestMessage(db *sql.DB, conversationId uuid.UUID) (*model.Contact, error) {
 	var latestMessage model.Contact
 
-	query := `
-  	  SELECT DISTINCT ON (m.conversation_id)
-  	    m.message_id AS last_message_id,
-  	    m.content AS last_message,
-  	    m.sent_at AS last_message_time,
-  	    a.username AS last_message_sender
-  	  FROM Messages m
-  	  JOIN Accounts a ON m.user_id = a.user_id
-  	  WHERE m.conversation_id = $1
-  	  ORDER BY m.conversation_id, m.sent_at DESC
-  	  LIMIT 1;
-  	`
+	err := db.QueryRow(`
+        SELECT DISTINCT ON (m.conversation_id)
+            m.message_id AS last_message_id,
+            m.content AS last_message,
+            m.sent_at AS last_message_time,
+            a.username AS last_message_sender
+        FROM Messages m
+        JOIN Accounts a ON m.user_id = a.user_id
+        WHERE m.conversation_id = $1
+        ORDER BY m.conversation_id, m.sent_at DESC
+        LIMIT 1;
+    `, conversationId).Scan(
+		&latestMessage.LastMessageID,
+		&latestMessage.LastMessage,
+		&latestMessage.LastMessageTime,
+		&latestMessage.LastMessageSender,
+	)
 
-	err := db.QueryRow(query, conversationId).Scan(&latestMessage.LastMessageID, &latestMessage.LastMessage, &latestMessage.LastMessageTime, &latestMessage.LastMessageSender)
 	if err != nil {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error getting latest message: %w", err))
+		if errors.Is(err, sql.ErrNoRows) {
+			return &model.Contact{}, nil // Return empty contact if no messages
+		}
+		return nil, helpers.NewError(helpers.ErrInternal, "Failed to get latest message", err)
 	}
+
 	return &latestMessage, nil
 }
 
@@ -315,21 +286,21 @@ func GetContacts(db *sql.DB, userID uuid.UUID) ([]*model.Contact, error) {
 
 	rows, err := db.Query(contactsQuery, userID)
 	if err != nil {
-		log.Println("Failed to get contacts:", err)
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error getting contacts: %w", err))
+		return nil, helpers.NewError(helpers.ErrInternal, "Failed to get contacts", err)
 	}
 
 	var contacts []*model.Contact
 	for rows.Next() {
 		contact := &model.Contact{}
-		err := rows.Scan(&contact.ID, &contact.UserID, &contact.Username, &contact.ConversationID, &contact.Type)
+		err := rows.Scan(&contact.ID, &contact.UserID, &contact.Username,
+			&contact.ConversationID, &contact.Type)
 		if err != nil {
-			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error scanning contact: %w", err))
+			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", err)
 		}
 
 		latestMessage, err := GetLatestMessage(db, contact.ConversationID)
 		if err != nil {
-			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error getting latest message: %w", err))
+			return nil, err
 		}
 
 		contact.LastMessageID = latestMessage.LastMessageID
@@ -341,7 +312,7 @@ func GetContacts(db *sql.DB, userID uuid.UUID) ([]*model.Contact, error) {
 	}
 
 	if err = rows.Err(); err != nil {
-		return nil, helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("error iterating over contacts: %w", err))
+		return nil, helpers.NewError(helpers.ErrInternal, "Failed to process contacts", err)
 	}
 
 	return contacts, nil
diff --git a/handlers/auth.go b/handlers/auth.go
index 9e21a43..b9e8949 100644
--- a/handlers/auth.go
+++ b/handlers/auth.go
@@ -1,11 +1,10 @@
 package handlers
 
 import (
-	"errors"
+	"fmt"
 	"github.com/gofiber/fiber/v2"
 	"github.com/golang-jwt/jwt/v5"
 	"golang.org/x/crypto/bcrypt"
-	"log"
 	"os"
 	"relay-server/config"
 	"relay-server/database"
@@ -14,154 +13,162 @@ import (
 )
 
 func Signup(c *fiber.Ctx) error {
-
 	type SignupStruct struct {
 		Username string `json:"username" xml:"username" form:"username"`
 		Password string `json:"password" xml:"password" form:"password"`
 	}
 
-	db := database.DB
 	u := new(SignupStruct)
 	if err := c.BodyParser(u); err != nil {
-		return err
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid request body", err)
 	}
-	// Checks if username or passwords are empty
+
+	// Validate input
 	if u.Username == "" {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "username is empty"})
+		return helpers.NewError(helpers.ErrInvalidInput, "Username is empty", nil)
 	}
 	if u.Password == "" {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "password is empty"})
+		return helpers.NewError(helpers.ErrInvalidInput, "Password is empty", nil)
 	}
-
-	// Checks if passwords or username have valid length and characters
 	if !helpers.IsValidPassword(u.Password) {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid password"})
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid password", nil)
 	}
 	if !helpers.IsValidUsername(u.Username) {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid username"})
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid username", nil)
 	}
 
-	// Checks if username already exist in database
-	exist, _ := database.CheckUserExists(db, u.Username)
+	// Check if user exists
+	exist, err := database.CheckUserExists(database.DB, u.Username)
+	if err != nil {
+		return helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to check user existance: %w", err))
+	}
 	if exist {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "user already exists"})
+		return helpers.NewError(helpers.ErrInvalidInput, "User already exists", nil)
 	}
 
 	// Create password hash
 	passwordHash, err := bcrypt.GenerateFromPassword([]byte(u.Password), config.BCRYPT_COST)
 	if err != nil {
-		log.Printf("error hashing password: %w\n", err)
-		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": "internal server error"})
+		return helpers.NewError(helpers.ErrInternal, "internal server error", fmt.Errorf("failed to generate password hash: %w", err))
 	}
 
-	// Insert username and password hash to database
-	userID, err := database.InsertUser(db, u.Username, string(passwordHash))
+	// Insert user
+	userID, err := database.InsertUser(database.DB, u.Username, string(passwordHash))
 	if err != nil {
-		log.Print(err)
-		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": "Internal server error"})
+		return helpers.NewError(helpers.ErrInternal, "Failed to create user", err)
 	}
 
-	// Generate token with user id and username
+	// Generate token
 	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
 		"user_id":  userID,
 		"username": u.Username,
 	})
-	// Sign token
 	signedToken, err := token.SignedString([]byte(os.Getenv("JWT_SECRET")))
+	if err != nil {
+		return helpers.NewError(helpers.ErrInternal, "Failed to generate auth token", err)
+	}
 
-	// Set token to cookies
+	// Set token cookie
 	tokenCookie := new(fiber.Cookie)
 	tokenCookie.Name = "token"
 	tokenCookie.Value = signedToken
 	tokenCookie.Expires = time.Now().Add(30 * 24 * time.Hour)
-	//tokenCookie.HTTPOnly = true
 	c.Cookie(tokenCookie)
 
-	// If everything went well sent username and user_id assigned by database
-	return c.Status(fiber.StatusOK).JSON(fiber.Map{"message": "Successfully signed up", "username": u.Username, "user_id": userID})
+	return c.Status(fiber.StatusOK).JSON(fiber.Map{
+		"message":  "Successfully signed up",
+		"username": u.Username,
+		"user_id":  userID,
+	})
 }
 
 func Login(c *fiber.Ctx) error {
-
 	type loginStruct struct {
 		Username string `json:"username" xml:"username" form:"username"`
 		Password string `json:"password" xml:"password" form:"password"`
 	}
 
-	db := database.DB
 	u := new(loginStruct)
-
 	if err := c.BodyParser(u); err != nil {
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid request body", err)
+	}
+
+	// Validate input
+	if u.Username == "" {
+		return helpers.NewError(helpers.ErrInvalidInput, "Username is empty", nil)
+	}
+	if u.Password == "" {
+		return helpers.NewError(helpers.ErrInvalidInput, "Password is empty", nil)
+	}
+	if !helpers.IsValidUsername(u.Username) {
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid username", nil)
+	}
+	if !helpers.IsValidPassword(u.Password) {
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid password", nil)
+	}
+
+	// Check if user exists
+	exist, err := database.CheckUserExists(database.DB, u.Username)
+	if err != nil {
+		return err
+	}
+	if !exist {
+		return helpers.NewError(helpers.ErrNotFound, "User does not exist", nil)
+	}
+
+	// Verify password
+	passwordHash, err := database.GetPasswordHash(database.DB, u.Username)
+	if err != nil {
+		return err
+	}
+	if err := bcrypt.CompareHashAndPassword([]byte(passwordHash), []byte(u.Password)); err != nil {
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid password", nil)
+	}
+
+	// Get user ID
+	userID, err := database.GetUserID(database.DB, u.Username)
+	if err != nil {
 		return err
 	}
 
-	// Checks if username or passwords are empty
-	if u.Username == "" {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "username is empty"})
-	}
-	if u.Password == "" {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "password is empty"})
-	}
-
-	// Checks if username or passwords have valid length and characters
-	if !helpers.IsValidUsername(u.Username) {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid username"})
-	}
-	if !helpers.IsValidPassword(u.Password) {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid password"})
-	}
-
-	// Checks if username exist in database
-	exist, _ := database.CheckUserExists(db, u.Username)
-	if !exist {
-		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "user does not exists"})
-	}
-
-	// Verifies password matching
-	passwordHash, err := database.GetPasswordHash(db, u.Username)
-	if err != nil {
-		log.Printf("error getting password: %w\n", err)
-	}
-	if bcrypt.CompareHashAndPassword([]byte(passwordHash), []byte(u.Password)) != nil {
-		return c.Status(fiber.StatusUnauthorized).JSON(fiber.Map{"error": "invalid password"})
-	}
-
-	userID, err := database.GetUserID(db, u.Username)
-	if err != nil {
-		var e *helpers.Error
-		if errors.As(err, &e) {
-			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"message": "user does not exist"})
-		}
-		log.Println(err)
-		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"message": "Internal server error"})
-	}
-	// Generate token with user id and username
+	// Generate token
 	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
 		"user_id":  userID,
 		"username": u.Username,
 	})
-	// Sign token
 	signedToken, err := token.SignedString([]byte(os.Getenv("JWT_SECRET")))
+	if err != nil {
+		return helpers.NewError(helpers.ErrInternal, "Failed to generate token", err)
+	}
 
-	// Set token to cookies
+	// Set token cookie
 	tokenCookie := new(fiber.Cookie)
 	tokenCookie.Name = "token"
 	tokenCookie.Value = signedToken
 	tokenCookie.Expires = time.Now().Add(30 * 24 * time.Hour)
 	c.Cookie(tokenCookie)
 
-	return c.Status(fiber.StatusOK).JSON(fiber.Map{"message": "Successfully logged in", "username": u.Username, "user_id": userID})
+	return c.Status(fiber.StatusOK).JSON(fiber.Map{
+		"message":  "Successfully logged in",
+		"username": u.Username,
+		"user_id":  userID,
+	})
 }
 
 func ValidateToken(c *fiber.Ctx) error {
-	username := c.Locals("username").(string)
-	userID := c.Locals("userID").(string)
+	username, ok := c.Locals("username").(string)
+	if !ok {
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid token: missing username", nil)
+	}
 
-	//log.Printf("userID: %v, username: %v", userID, username)
-	//if userID == "" || username == "" {
-	//	log.Printf("userID or username is empty %v", c.Locals("username"))
-	//	return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid token"})
-	//}
+	userID, ok := c.Locals("userID").(string)
+	if !ok {
+		return helpers.NewError(helpers.ErrInvalidInput, "Invalid token: missing user ID", nil)
+	}
 
-	return c.Status(fiber.StatusOK).JSON(fiber.Map{"message": "authorized", "username": username, "user_id": userID})
+	return c.Status(fiber.StatusOK).JSON(fiber.Map{
+		"message":  "authorized",
+		"username": username,
+		"user_id":  userID,
+	})
 }
diff --git a/handlers/contacts.go b/handlers/contacts.go
index 5127270..0011f54 100644
--- a/handlers/contacts.go
+++ b/handlers/contacts.go
@@ -25,13 +25,10 @@ func DeleteContact(c *fiber.Ctx) error {
 		return helpers.NewError(helpers.ErrInvalidInput, "conversation ID is empty", nil)
 	}
 
-	msg, err := database.DeleteContact(database.DB, p.ContactID, p.ConversationID)
+	err := database.DeleteContact(database.DB, p.ContactID, p.ConversationID)
 	if err != nil {
 		return helpers.NewError(helpers.ErrInternal, "Failed to delete contact", err)
 	}
-	if msg != "" {
-		return helpers.NewError(helpers.ErrInvalidInput, msg, nil)
-	}
 
 	return c.Status(fiber.StatusOK).JSON(fiber.Map{"message": "Contact deleted"})
 }